Neonatal Mouse Brainstem Electrophysiology

Dbx1 reporter mouse pups and wild‐type littermates were anesthetized at postnatal days 0–4 (P0‐4) by immersion in crushed ice until disappearance of the tail pinch response. After isolation within 1–2 min, the neuraxis from the pons to the rostral cervical spinal cord was transferred to a dish filled with superfusate containing (in mmol·L⁻¹): 124 NaCl, 3 KCl, 1.5 CaCl₂, 1 MgSO₄, 25 NaHCO₃, 0.5 NaH₂PO₄, and 30 dextrose, equilibrated with carbogen, a mixture of 95% O₂ and 5% CO₂ to establish a pH of 7.4. After removing the arachnoidea, the neuraxis of P0‐4 mice was used for electrophysiological experiments, which were performed in the Del Negro laboratory at The College of William & Mary. Anatomical analyses of chemically fixed preparations from P0 or P4 mice in the Ballanyi laboratory at the University of Alberta.