Fig. 3.

Nucleus accumbens dopamine concentrations in rats receiving experimenter-administered intravenous doses of d-amphetamine (0.25 mg/kg per injection).Top, These four rats (experienced–yoked) had a history of amphetamine self-administration. Bottom, These four rats (inexperienced–yoked) were naïve to amphetamine and self-administration. Dialysate samples were collected at 10 min intervals before the start of the session at time = 0 (baseline) and at 5 min intervals after the start of the session. Vertical dotted lines represent the receipt of d-amphetamine infusions. A and DL numbers are rat identification numbers.