Fig. 7: Activation of the SC–SNc pathway promoted appetitive locomotion.

a Schematic diagram showing injection of AAV-ChR2-mCherry into the SC of WT mice, followed by optical fiber implantation above the SNc. b An example coronal section of ventral midbrain with an optical-fiber track above the ChR2-mCherry+ axon terminals in the SNc (left), the boundary of which was delineated by the immunofluorescence of TH (right). This experiment was repeated independently in 12 mice with similar results. c Schematic diagram showing the experimental configuration to monitor mouse locomotor behavior in the linear runway. d Time courses of locomotion speed of control (Ctrl) and test mice (ChR2) in the linear runway before, during and after light stimulation of the SC–SNc pathway (10 Hz, 20 ms, 6 s, 10 mW). e Quantitative analyses of average locomotion speed of control (Ctrl) and test mice (ChR2) before, during, and after photostimulation of the SC–SNc pathway. f Schematic diagram showing the experimental configuration to monitor predatory hunting in the arena. g, h Behavioral ethograms showing the time courses of locomotion speed (top) and jaw attacks (bottom) during predatory hunting of an example mouse without (g) and with (h) photostimulation of the SC–SNc pathway (10 Hz, 20 ms, 10 mW). The shaded areas (orange) indicated the approach episodes in predatory hunting. For the analyses of azimuth angle and PPD, see Supplementary Fig. 10j, k. i–m Speed of approach (i), frequency of approach (j), time to capture (k), latency to attack (l), and frequency of attack (m) in predatory hunting of mice without (OFF) and with (ON) photostimulation of the SC–SNc pathway. Number of mice was indicated in the graphs (d, e, i–m). Data in d, e, i–m are means ± SEM (error bars). Statistical analyses in e, i–m were performed by one-sided Student’s t-tests (^n.s.P > 0.1; ***P < 0.001). Scale bars are indicated in the graphs.