9 events/condition/phase; M20, 82.8 events/condition/phase). The injection run was excluded from fMRI analysis but consisted of 2 small bolus injections (duration 30 s) via a jugular catheter, of (0.0025–0.005 mg/kg) selective D1 Ribociclib price antagonist R(+)-SCH-23390 hydrochloride (Sigma-Aldrich; St Louis, MO) five minutes apart. In any given session, both injections were of the same concentration. Two injections were administered rather than a single dose to limit potential extrapyramidal effects associated with peak concentrations of dopamine antagonist (Fischer et al., 2010). Each animal participated in 5 sessions,

resulting in 15 runs/phase/animal and 30 runs/phase in total. Injection of SCH-23390 into rats has been shown to have a 30 min half-life in plasma while displaying a slightly longer half-life of 40–60 min in the striatum and cortex (Hietala et al., 1992). Therefore, the runs following the post-injection phase were deemed the recovery phase with the caveat that physiological relevant levels of SCH-23390 may still be present in the brain, albeit at a lower concentration than in the postinjection phase. Each session contained a cue-reward association

block BYL719 and two free-choice stimulus preference tests (400 trials). The first preference test preceded the association block while the second test immediately followed it. Preference tests were used to assess potential changes in stimulus preference. Stimulus preference trials began when the animal fixated on a central fixation point. After 1,000–1,500 ms, two stimuli (∼7-deg in size) were simultaneously presented peripheral Bumetanide (9.5-deg eccentricity) to the fixation point for up to 2,000 ms, one to the left and the other to the right of the fixation point. For each session, two novel stimuli were chosen from a randomized set of basic geometric shapes that differed in both

shape and color. A trial was completed and the stimuli were removed after a saccade to one of the two stimuli. The position of the stimuli was randomly alternated and both stimuli were rewarded with a 50% reward probability. After testing stimulus preference, the less-selected stimulus (i.e., non-preferred stimulus) was associated with a juice reward during 25 cue-reward trials within a cue-reward association block. There were two variants of the cue-reward association blocks, those that contained uncued reward trials and those that did not. Association blocks with uncued reward were identical to experiment 1 and therefore contained 4 equiprobable trial types (fixation, reward, cue, cue-reward). Association blocks without uncued reward contained 2 equiprobable trial types (cue and cue-reward). After the cue-reward association block another stimulus preference test was performed. Analysis was performed in 20 trial bins comparing nonpreferred stimulus selection before and after the two different types of cue-reward association blocks.