Fig. 4.

Nonlocalized CS+ control group replicates the enhancement of the conditioned incentive effect of amphetamine. Lever pressing for sucrose under extinction conditions (after microinjection of amphetamine or vehicle) by the control group of rats that received Pavlovian training with auditory CS+ and CS− (tone vs clicker). Amphetamine microinjection selectively enhanced sucrose lever pressing in the presence of the auditory CS+ for sucrose. Pressing on the lever was not enhanced by amphetamine in the absence of the auditory CS+ or in the presence of the auditory CS−.