The AAVs were injected into the prefrontal cortex of P0–P1 mouse pups. Neonatal mice were first cryo-anesthetized in an ice-cold chamber, and then secured in a prone position with a custom-made clay mold and adhesive bandage. A syringe pump injector equipped with pulled glass micropipette of beveled tip at ~50 µm diameter was used for injections. The insertion location of micropipette was guided by vascular anatomy, rostral to inferior cerebral vein and close to superior sagittal sinus. Each pup received one injection in only one hemisphere, with a total of 0.5 µl of AAV suspension at 2 different depths. The overall survival was nearly 100%. The injected pups were sacrificed at P7–8, and the brains were harvested for dissection of infected tissues marked by green fluorescence under blue-light illumination from a hand-hold LED lamp (Nightsea Inc., excitation 440–460 nm, see Fig. S7H) The dissected tissues were then lysed for immunoblotting and qPCR (Fig. 7A–7C, S7I–S7J).
