Anterograde trans-synaptic viral labeling

Anesthesia was induced with 125 mg/kg ketamine and 5 mg/kg xylazine. Male PV-Cre and both male and female Ai6 mice were secured in a stereotaxic frame, and bilateral injections of 200–300 nl adeno-associated virus (AAV)1 vectors (AAV1-EF1a-DIO-ChETA-eYFP (catalog #26968, Addgene) to PV-Cre mice and pENN-AAV1-hSyn-Cre-WPRE-hGH (catalog #105553, Addgene) to Ai6 mice) were aimed with a 3 nl/s flow rate at the following coordinates from bregma (in cm): for BA injections, AP, −0.15; ML, 0.32–0.35; DV, 0.44–0.50; for midline thalamus injections, AP, −0.12–0.13; ML, next to the sinus; DV, 0.30–0.33; for lateral entorhinal cortex (LEnt) injections, AP, −0.42; ML, 0.375; DV, 0.28. After 4 weeks of recovery, mice were transcardially perfused with 4% PFA in 0.1 m PB for 30–40 min, and PFC sections were prepared as described above.