Pharmacologic magnetic resonance imaging (phMRI): Imaging drug action in the brain

► Drug-induced phMRI changes reflect receptor distributions, function and signaling. ► Selective pharmacologic challenges can open the black box of neurovascular coupling. ► Most drug stimuli produce positive and negative hemodynamic responses. ► Pharmacodynamics and pharmacokinetics can potentially be measured with phMRI. ► PhMRI is a molecular imaging tool with very high sensitivity rivaling PET.