Fig. 5.

Ester lines from saline and cocaine self-administration sessions under the FR 1 schedule of reinforcement in a wild-type mouse and a DATki mouse. Sessions lasted 3 h or until 100 reinforcers were earned, or, for 3.2 mg/kg per infusion of cocaine, until 10 reinforcers were earned, to prevent overdose. Cocaine maintained typical patterns of responding in the wild-type mice, but more erratic patterns in the DATki mice. Note also the high rate of responding maintained by a peak cocaine dose in the wild-type mouse (0.32 mg/kg per infusion).