DLC analysis confirms that inhibition of VTA dopamine neurons suppresses sign-tracking behavior. Data are mean ± SEM for approach behavior directed toward the (a,b) lever-cue (left) or (c,d) food magazine (right) during the (a,c) 8.2 s lever-cue presentation (top) or (b,d) after lever retraction, during the ITIs (bottom). An approach bout was counted when the rat's nose remained within 75 pixels (1 cm) of the lever-cue or food magazine during >15 frames (1 s). A bout ended when the interbout interval exceeded 15 frames. Relative to control rats, eNpHR rats exhibit less approach behavior toward the lever-cue, and this is true (a) during lever-cue presentation and (b) after lever-cue retraction (during the ITIs). Approach behavior directed toward the food magazine does not differ between control rats and those in the eNpHR group. **p < 0.01. ***p < 0.001.