The rAAV5-Ef1a-DIO-hChR2-eYFP, AAV9-CAG-Flex-GFP, and AAV8-hSyn-DIO-KORD-IRES-mCitrine were produced by the University of North Carolina vector core facility (Chapel Hill, North Carolina, USA). The pAAV-Syn-Flex-GCaMP6f-WPRE-SV40 (Catalog number 100833), AAV-Ef1a-DIO-GCaMP6f-P2A-nls-tdTomato (retrograde AAV; Catalog number 51083), pAAV-EF1a-fDIO-Cre (retrograde AAV; Catalog number 121675-AAVrg), pAAV_hSyn1-SIO-stGtACR2-FusionRed (Catalog number 105677-AAV1), pAAV-hSyn-DIO-EGFP (retrograde AAV; Catalog number 50457-AAVrg) and pAAV-hSyn-DIO-mCherry (retrograde AAV; Catalog number 50459-AAVrg) were produced by Addgene (Watertown, MA, USA). The CAV-Flex-FlpO was produced by Montpellier vector platform (Plateforme de Vectorologie de Montpellier (PVM), Biocampus Montpellier, Montpellier, France). The AAVDJ-CAG-fDIO-oG-WPRE-SV40pA was produced by the Viral Vector Core Facility at Salk Institute. The AAV2/8-Ef1a-fDIO-TVA-mCherry was produced by Z. Josh Huang’s lab at CSHL. The Rbv-CVS-N2c-dG-GFP (the optimized rabies virus)36 (link) was produced by HHMI Janelia Research Campus. The AAV8-CaMKIIa-FDO-GCaMP6f (Flp-off) virus was produced by K. Deisseroth’s lab at Stanford University. All viral vectors were aliquoted and stored at –80 °C until use.