The effects of cocaine self-administration on rates of local cerebral glucose utilization across the anterior–posterior extent of the core (top) and shell (bottom) subdivisions of the ventral striatum of rhesus monkeys. Rates of glucose utilization of monkeys in the initial (5 d experience) and chronic (100 d experience) stages of self-administration are compared with rates of glucose utilization of control monkeys in which responding was maintained by food. Asterisks mark statistically significant differences (p < 0.05) from control. The vertical line in each panel represents the level of the anterior commissure. Note that glucose utilization is significantly reduced in both shell and core at both time points, but is reduced in the more rostral pole portion of the accumbens only at later time points.