Enhancement of incentive motivation by CRF. Effects on cue-triggered lever pressing during extinction test caused by CRF (250 and 500 ng) and amphetamine (20 μg) microinjections in the caudal medial accumbens shell. A. Lines show pressing in the presence of the CS+ (previously associated with sucrose- red circles); and CS- (never associated with sucrose- blue circles); and pre-CS+ baseline period (no-stimulus 30 sec period immediately prior to CS+ stimulus); and pre-CS- baseline period (30 sec immediately prior to CS- stimulus). The left panel depicts lever pressing on the control lever that had previously produced instrumental sucrose reward during training (but not during extinction test). The right panel depicts lever pressing on the control lever that was never had produced reward. Both 500 ng CRF and 20 μg amphetamine increased the ability of the sucrose CS+ cue (but not CS-) to trigger enhanced responding on the previously sucrose-associated lever (but not on the control lever). B. Transform scores show a direct contrast between CS+ and CS- effects of lever pressing. CS+ effects on cue-triggered lever pressing are amplified by CRF (500 ng) and by amphetamine (20 μg) microinjections.