Acute brain slice preparation

Acute slices were prepared from 2–4-months-old male and female mice. Animals were briefly anesthetized with CO₂ and decapitated. Brains were removed quickly and placed in cold (~10 °C), sucrose-based oxygenated (95% O₂–5% CO₂) cutting solution composed of (in mM) sucrose 234, glucose 11, NaHCO₃ 26, KCl 2.5, NaH₂PO₄ H₂O 1.25, MgSO₄*7H₂O 10, and CaCl₂ H₂O 0.5. Coronal slices containing the PmCo were obtained with a slicing vibratome (VT1200s; Leica, Wetzlar, Germany). The brains were trimmed by removing the cerebellum with a perpendicular cut to the rostral–caudal plane and the caudal brain surface was glued (Superglue Loctite 401 20G, Loctite) to the vibratome stage submerged in cold cutting solution. Slice thickness was 300 μm for all experiments. The slices were immersed in oxygenated (95% O₂/5% CO₂) artificial cerebral spinal fluid (ACSF) at 34 °C for 30–45 min. ACSF was composed of (in mM) NaCl 126, NaHCO₃ 26, glucose 10, KCl 2.5, NaH₂PO₄ H₂O 1.25, MgCl₂*6H₂O 2, and CaCl₂*2H₂O 2, pH 7.4, with osmolarity maintained at 290–300 mOsm.