Principle behind the fMRI scan experiment about the activation of the striatum in the anticipation of rewards.

A. Students saw a series of images on the computer screen in the MRI machine. The square shape was never followed by a reward outcome (the jar of coins). The diamond shape was followed by a reward outcome 66% of the time. B. For students who didn’t have ADHD, you see places in the striatum (where the red circle is) lighting up (in bright colors) during the period of waiting, but not during reward. C. For students who had ADHD, you see places in the striatum (where the red circle is) lighting up when they actually saw the jar of coins, but not while they were waiting for it. In both panels (B,C), the lighter yellow color shows greater activation.