The authors administered 48 mg of intravenous cocaine or placebo to
eight abstinent cocaine users in a double-blind, crossover design and
examined blood flow using single photon emission computed tomography.
Cocaine produced significant decreases in frontal cortical and basal
ganglia blood flow; these latter correlated negatively with increases in
self-ratings of "rush" and "high." The authors conclude that these local
effects are compatible with dopaminergic system involvement.