Histology
Electrode placements were verified via electrophoretic ejection of Chicago Sky Blue dye (Sigma) at the recording site. Rats were euthanized with a lethal dose of pentobarbital (182.2 mg/kg, IP), and brains were removed. The tissue was fixed in 8% paraformaldehyde for at least 48 h and transferred to a 25% sucrose solution for cryoprotection. Once saturated, the brains were frozen and sliced coronally at 60 μm thick using a cryostat (Thermo Scientific™ Cryostat CryoStar™ NX70) and mounted onto gelatin-coated slides. Tissue was stained with a combination of neutral red and cresyl violet. Only rats with verified electrode placements for both recording and infusion sites were included in the data analysis.