Significant Group × Session interaction (p<0.05, corrected) during the anticipation phase of our gambling task (left panel).

<p>To illustrate the nature of the interaction effect, the middle panel shows parameter estimates (in the order placebo at scan 1, placebo at scan 2, AS at scan 1 (before sensitisation), AS at scan 2 (after sensitisation) from the mean response within an associative striatal ROI. The graph on the right shows the correlation between sensitisation-related change in striatal BOLD signal during anticipation and the change in subjective response to amphetamine. All parameter estimates reflect the mean response in arbitrary BOLD units. Results are shown with the standard error of the mean.</p

Upper Panel: Brain regions identified as displaying sensitivity to the task phases (i.e. decision, anticipation, wins and losses) in the placebo group (left panel).

<p>Parameter estimates for key dopaminergic and reward-related areas showing a significant main effect of task (right panel). Lower Panel: Brain regions where BOLD signal was modulated by reward probability the placebo group (left panel). Parameter estimates from the occipital cortex and precuneus, regions that display a significant main effect of reward probability. All parameter estimates reflect the mean response in arbitrary BOLD units. Results are shown with the standard error of the mean.</p