Fig. 1: Anterograde and retrograde tracings of CN^GLU → ZI and CN^GABA → ZI circuits.

a Schematic illustrating the viral injection and components of the AAV2/9 virus. b Left: viral infection (yellow) in CN^GLU neurons of vGluT2-Cre mice; bregma: −6.20. Right: CN^GLU axonal tracts and terminals in contralateral ZI; bregma: −2.50. Scale: 200 μm. The inset shows axonal terminals (Scale: 50 μm). This experiment was repeated in 4 mice. c Left: Viral infection (yellow) in CN^GABA neurons of vGat-Cre mice; bregma: −6.20. Right: CN^GABA axonal tracts and terminals in contralateral ZI; bregma: −2.50. Scale: 200 μm. The inset shows the axonal terminals (Scale: 50 μm). This experiment was repeated in 4 mice. d Experimental design for retrograde transsynaptic viral injection and immunostaining. e The upper panel displays ZI-GLU neurons infected by a virus with a dashed line outlining the ZI area; bregma: −2.50. Scale: 200 μm. Starter cells labeled by EGFP and dsRed are indicated by white arrows. The lower panel shows traced contralateral CN neurons (white arrows) labeled by RV and GABA staining with a dashed line outlining IN and DN; bregma: −6.20. Scale: 25 μm. This experiment was repeated in 4 mice. f The proportion of _ZI-GLUCN neurons in the total CN neurons (n = 30 sections; 3 mice). g The proportions of _ZI-GLUCN^GABA and _ZI-GluCN^SMI32 neurons (n = 713). h Upper panel: ZI-GABA neurons infected by virus; bregma: −2.50. Scale: 200 μm. Starter cells were labeled by EGFP and dsRed. Lower panel: traced contralateral CN neurons (bregma: −6.20) labeled by RV virus and SMI32. Note that the enlarged figures have been rotated 90 degrees. Scale: 25 μm. This experiment was repeated in 4 mice. i The proportion of _ZI-GABACN neurons in total CN neurons (n = 30 sections; 3 mice). j The proportions of _ZI-GABACN^SMI32 and _ZI-GABACN^GABA neurons (n = 951). Source data are provided as a Source Data file.