Fig. 2

Respiratory rhythm bursts in the brainstem spinal-cord preparation and the upper cervical slice preparations. a Rhythmic respiratory bursts, marked by dots, were obtained from the C1, C2, and C4, ventral roots in the brainstem spinal-cord preparation. Synchronized rhythmic respiratory bursts were recorded from the C1–C4 ventral roots. These bursts were synchronized with XIIth nerve activity. b After transection A, at the upper border of C1, the respiratory bursts persisted but with lower and irregular burst frequencies. c After transection B, at the lower border of C2 (shown in Fig. 1), respiratory bursts in the C2 roots were observed with lower frequencies, but the burst activity in the C4 ventral root was eliminated. d A summary of the respiratory burst frequencies before and after transections does not show any significant difference between each of the groups [Before before transection, A after transection at level A, A–B upper cervical slice (A–B); n = 5 each, paired t tests]