Dopaminergic mechanisms play a role in all forms of action inhibition. For example, response inhibition in the stop signal task is impaired after pharmacological blockade of dorsomedial striatal dopamine D2-like receptors, while D1-like receptor blockade in the same brain region increases inhibition in this task.146 Further supporting these results, D2-like receptor stimulation improves stop signal inhibition in humans,147 and individual differences in striatal dopamine D2-like receptor availability, measured with positron emission tomography, vary negatively with the stop signal reaction times.148
