CONTEXT: Recent work suggests that the amphetamine sensitization model of schizophrenia can safely be induced in healthy volunteers and is associated both with behavioral and dopaminergic hypersensitivity to amphetamine. However, the effects of a sensitization on brain function remain unclear. OBJECTIVE: To assess the impact of a sensitizing dosage regimen of dextroamphetamine on human cortical functioning and cognition. DESIGN: Randomized, double-blind, parallel-groups design using pharmacological functional magnetic resonance imaging. SETTING: The neuroimaging research unit at the Institute of Psychiatry, King’s College London, London, England. PARTICIPANTS: Healthy male volunteers (n = 22). INTERVENTIONS: Dextroamphetamine (20 mg) or placebo administration at 4 testing sessions, using a dosage regimen shown to induce sensitization (ie, 3 doses administered with a