Inhibition of VTA dopamine neurons blunts the orienting responses to the lever-cue. a, Left, Head orientation was calculated from each video frame and is depicted as a unit vector on a polar histogram with the relative location of the magazine, lever, and back of chamber labeled. Right, Representative frame from a video with magazine and lever labeled. Marker labeling from Deep Lab Cut: nose (purple), tether (green), shoulders (orange/yellow), tail (blue), and magazine (red). Head orientation was calculated from the angle between two vectors: (1) from the tether to the nose and (2) from the tether to the magazine. b–f, Polar histograms showing individual rat average head direction (left) and group data head direction (center/right) (b) before lever-cue presentation (4 s), (c) during lever-cue presentation (4 s), (d) before pellet delivery (4 s), (e) after pellet delivery (4 s), and (f) during the ITI (4 s). c, Compared with controls, eNpHR rats that received inhibition of dopamine neurons in the VTA had more variability in their head direction during lever-cue presentation. *p < 0.05.