Acute brain slice preparation.

Acute brain slices were obtained from Swiss Webster (Taconic) mice at P11 to P22, using standard techniques. Mice were used without regard for sex. No statistical methods were used to estimate sample size for animal studies throughout. No randomization or blinding were used for animal studies throughout. Mice were anaesthetized by isoflurane inhalation, decapitated and cerebral hemispheres were quickly removed and placed in cold choline-based cutting solution consisting of (in mM): 110 choline chloride, 25 NaHCO₃, 2.5 KCl, 7 MgCl₂, 0.5 CaCl₂, 1.25 NaH₂PO₄, 25 glucose, 11.6 ascorbic acid, and 3.1 pyruvic acid (339–341 mOsm/kg; pH 7.75 adjusted with NaOH) for 2 min, blocked and transferred into a slicing chamber containing ice-cold choline-based cutting solution. Coronal slices (300 μm thick) were cut with a Compresstome VF-300 slicing machine, transferred to a holding chamber with artificial cerebrospinal fluid (ACSF) containing (in mM) 125 NaCl, 2.5 KCl, 25 NaHCO₃, 2 CaCl₂, 1 MgCl₂, 1.25 NaH₂PO₄ and 11 glucose (300–310 mOsm/kg; pH 7.35 adjusted with NaOH), and recovered for 10 min at 34 °C, followed by another 30 min at room temperature. Slices were subsequently maintained at room temperature until use. Both cutting solution and ACSF were constantly bubbled with 95% O₂ and 5% CO₂.