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.