Table 1.

Summary of Network Properties of Cultured Brainstem Neurons

	PCO2 38 torr		70 torr
	mean	S.D.	mean	S.D.	# U	# D	P
CO2-stimulated units
Peak-mean ratio (total)	5.62	7.10	7.55	10.09	106	4	<0.001
Peak-mean ratio (pericentral)	6.92	8.82	9.80	12.60	62	4	<0.001
Pericentral peak latency (ms)	1.85	1.89	1.52	1.26	62	4	0.01
Pericentral peak width (ms)	0.72	0.39	0.76	0.47	62	4	0.19
Peak-mean ratio (central)	3.78	2.19	4.39	2.65	44	4	0.003
Central peak width (ms)	0.77	0.66	0.91	0.60	44	4	0.03
Electrical coupling efficiency	0.80	0.11	0.39	0.18	5	3	0.006
Trough/mean ratio	0.23	0.17	0.22	0.17	6	3	0.33
Trough latency (ms)	3.40	0.83	3.20	0.91	6	3	0.15
Trough width (ms)	1.37	0.51	1.83	0.78	6	3	0.03
CO2-unresponsive units
Peak-mean ratio (total)	11.14	29.88	10.69	24.97	221	4	0.45
Peak-mean ratio (pericentral)	11.61	29.42	11.31	24.63	168	4	0.61
Pericentral peak latency (ms)	2.41	1.94	2.39	2.07	168	4	0.94
Pericentral peak width (ms)	0.70	0.39	0.72	0.39	168	4	0.31
Peak-mean ratio (central)	9.66	31.52	8.72	25.99	53	4	0.29
Central peak width (ms)	0.86	0.73	0.95	0.73	53	4	0.13
Electrical coupling efficiency	0.88	0.14	0.82	0.29	13	10	0.21
CO2-inhibited units
Peak-mean ratio (total)	8.30	13.75	10.22	13.86	127	7	<0.001
Peak-mean ratio (pericentral)	7.87	13.69	9.77	13.12	93	7	<0.001
Pericentral peak latency (ms)	1.63	1.25	1.74	1.45	93	7	0.19
Pericentral peak width (ms)	0.73	0.48	0.70	0.39	93	7	0.09
Peak-mean ratio (central)	9.46	13.76	11.44	17.08	34	7	0.02
Central peak width (ms)	0.63	0.52	0.58	0.29	34	7	0.18

Differences between the PCO₂ levels were examined using Student t test with P value shown in the last column. Abbreviations: # D, number of dishes; # U, number of units; P, probability; S.D., standard deviation.