Cocaine activation discriminates dopaminergic projections by temporal response: An fMRI study in rat

We applied a sensitive new functional magnetic resonance imaging technique to identify the pattern and determinants of cocaine-induced brain activatio n in drug-naive rats. At doses greater than 0.1 mg/kg iv cocaine produced r obust activation throughout cortex with the largest magnitude increase in f rontal neocortex tex. Additionally, we detected selective activation within dopamine-innervated subcortical regions including dorsomedial and ventrola teral striatum, nucleus accumbens region, and dorsal thalamus. All though d ose response was similar among activated regions, temporal response differe ntiated regions along distinct anatomical boundaries with basal ganglia and limbic cortical structures, reaching maximum activation later than frontal neocortex. Pharmacological specificity was demonstrated by blocking cocain e-induced activation with SCH-23390, a selective D1 antagonist. Our data de monstrate the utility of fMRI to identify spatiotemporal patterns of cocain e-induced brain activation and implicate D1 dopaminergic mechanisms in acut e cocaine action. (C) 2000 Academic Press.