Table 1.

Respiratory neuron classification (classification in parentheses corresponds to scheme in Takeda et al., 1986), activity pattern, number of neurons, peak firing rate (mean ± standard deviation, range) derived from cycle-triggered histograms, and the number of intrinsically bursting neurons are shown (number of intrinsically bursting neurons/total number tested in that group).

Neuron classification	Activity pattern	Neurons (n)	Peak rate (Hz)	Intrinsically bursting neurons
E-cell (E)	peak activity and most activity during first two-thirds of XII burst	50	10.5 ± 9.5 (0.1–37.0)	3/38
EI-cell (E-i)	active throughout entire XII burst	133	15.1 ± 12.5 (0.8–53.0)	5/118
I-cell (I)	most activity during last third of XII burst	6	5.0 ± 3.7 (1.1–10.0)	1/6
Post-I-cell (PI)	peak activity at end of XII burst	3	2.5 ± 2.0 (1.2–4.8)	2/2
E-cell/Post-I- cell (pi-E)	similar to Post-I-cell, but with some activity during prior to or during first two-thirds of XII burst	11	6.8 ± 3.4 (1.6–12.0)	4/7
Pre-E-cell	peak activity prior to or at onset of XII burst	9	15.8 ± 12.7 (1.7–42.0)	1/6
Respiratory- related unit	peak activity during XII burst, but can’t be classified	7	2.3 ± 2.5 (0.4–7.1)	3/5