For IHC, 4 animals were anesthetized with isoflurane and transcardially perfused with cold Ringer’s solution containing 2% lidocaine HCl (20 mg/mL) and heparin (1000 USP units/mL) followed by 4% paraformaldehyde. Brains were harvested as previously described 19 (link). Immunostaining for tdTomato was performed with a 1:200 diluted mouse anti-DsRed antibody (Clontech, Mountain View, CA). For PVALB immunostaining, we used a 1:5,000 dilution of rabbit anti-parvalbumin primary antibody (Swant Ltd., Marly, Switzerland). CCK-stained sections were incubated with rabbit anti-proCCK (a generous gift from Dr Andrea Varro; 1:1000) for 72 h at 4°C, while NPY staining was performed using rabbit anti-NPY primary antibodies (Sigma, St Louis, MO, USA; 1:1000) . For fluorescence visualization, goat anti-rabbit Alexa Fluor 488 and goat anti-mouse Alexa Fluor 568 secondary antibodies were used (Life Technologies, Carlsbad, CA, USA) at 1:250 dilution. DAPI staining was performed using 3 min incubation in 300 nM DAPI (Sigma, St Louis, MO, USA). Rinsed brain slices where mounted on slides and cover-slipped in ImmunoMount (Fisher Scientific, Pittsburg, PA, USA). Imaging was performed using the EVOS imaging system and microscope (Life Technologies, Carlsbad, CA, USA).