FROM THE RUSH TO THE ADDICTION, COCAINE'S EFFECTS IN THE BRAIN.

(Brain inset) Cocaine causes euphoria in the short term and addiction in the long term via its effects on the brain’s limbic system, which consists of numerous regions, including the ventral tegmental area (VTA) and nucleus accumbens (NAc), centers for pleasure and feelings of reward; the amygdala and hippocampus, centers for memory; and the frontal cortex, a center for weighing options and restraint.

(Main panel) Cocaine causes the neurotransmitter dopamine to build up at the interface between VTA cells and NAc cells, triggering pleasurable feelings and NAc cellular activities that sensitize the brain to future exposures to the drug. Among the activities are increased production of genetic transcription factors, including ΔFosB; altered gene activity; altered production of potentially many proteins; and sprouting of new dendrites and dendritic spines.

(Graph inset) The time courses of cocaine-induced buildup of ΔFosB and cocaine-related structural changes (dendrite sprouting) suggest that these neurobiological effects may underlie some of the drug’s short-term, medium-term, and long-term behavioral effects.