Figure 1.

Pattern of spontaneous respiratory activity recorded in vitro from the isolated neonatal rat brainstem–spinal cord. A, D, Schematics of preparations with recording electrodes placed on cervical (C4 or C5), thoracic (T8), and lumbar (L1) spinal ventral roots. B1, E1, Different raw respiratory activities recorded in C4 or C5 (inspiratory-like), T8 (inspiratory- and expiratory-like), and L1 (expiratory-like) ventral roots. B2, E2, Expanded traces of respiratory bursts recorded in C4, C5, T8, and L1 ventral roots. C, Circular plot of the phase relationship between C4 inspiratory burst onset and L1 expiratory burst onset (n = 22 respiratory burst cycles).