Electrophysiological Recording in Mouse Brain Slices

The procedures used for the electrophysiological experiments were as described previously [26 (link),27 (link)]. Briefly, mice were decapitated under deep isoflurane anesthesia and brains were quickly removed in ice-cold dissection buffer containing sucrose (212.7 mM), KCl (2.6 mM), NaH₂PO₄ (1.23 mM), NaHCO₃ (26 mM), dextrose (10 mM), MgCl₂ (10 mM), and CaCl₂ (0.5 mM). Horizontal brain sections (400 μm thick) were prepared using a vibratome (Campden Instruments; Loughborough, UK) and placed in dissection buffer that was continuously bubbled with 95% O₂/5% CO₂ (v/v). The slices were held at 35 °C for 1 h in a chamber filled with continuously oxygenated artificial cerebrospinal fluid (ACSF) of the following composition: NaCl (124 mM), KCl (5 mM), NaH₂PO₄ (1.25 mM), NaHCO₃ (26 mM), dextrose (10 mM), MgCl₂ (1.5 mM), and CaCl₂ (2.5 mM). The slices were then transferred to a submersion recording chamber that was maintained at 30 °C, and perfused with oxygenated ACSF at a flow rate of 2 mL/min.