Striatal dopamine D2/D3 receptor regulation of human reward processing and behaviour

Dopamine is a brain chemical that directly enables the experience of motivation, reward, and pleasure when encountering environmental cues.

In healthy adults, taking 10 mg of aripiprazole daily for seven days does not reduce activity in the brain's reward center or cause negative symptoms, even though it produces motor side effects similar to those caused by drugs that fully block dopamine receptors.

In healthy adults, taking 400 mg of amisulpride daily for seven days reduces activity in the caudate region of the brain during reward processing and increases the severity of negative symptoms such as blunted affect and reduced speech.

Higher levels of the drug amisulpride in the blood correspond to a stronger decrease in activity in the caudate region of the brain when processing rewards, demonstrating a direct relationship between drug concentration and reduced neural reward response.

Blocking or partially activating dopamine D2/D3 receptors in healthy adults causes motor symptoms like restlessness and stiffness, but these symptoms do not relate to changes in brain reward responses, showing that motor and reward systems respond differently to dopamine changes.

Blocking dopamine D2/D3 receptors for an extended period reduces activity in the caudate nucleus when people receive a reward, but does not reduce activity when they expect a reward.