Fig. 1.

The level of the transverse section used for optical recordings. a Ventral view of a brainstem–spinal cord preparation from a neonatal rat. The preparation was cut at the level of the dotted line. b Rostral cut surface view of a preparation at a level of 0.5 mm rostral to the caudal end of the facial nucleus (ΔFNc). The square denotes the approximate recording area. c Schematic representation of the preparation in the recording chamber. The preparation was fixed onto a rubber block by pins with cut surface facing up for observation from the cut surface of the cross-section (arrow). AICA anterior inferior cerebellar artery, FN facial nucleus, pFRG parafacial respiratory group, preBötC preBötzinger complex, VII–XII cranial nerves, C4 the fourth cervical ventral root