Table 1.

Properties of spontaneously generated spike trains during development

	Control					Dark-reared
	P9	P11–13	P15	P21	6 weeks	P15	P21	6 weeks
Number of cells (retinas)	57 (3)	166 (8)	158 (4)	132 (4)	89 (4)	140 (5)	95 (4)	165 (6)
Firing rate (Hz)
Mean	0.30	0.45	0.96	0.70	2.40	0.95	1.29	2.49
25%	0.16	0.18	0.32	0.09	0.13	0.37	0.32	0.46
50%	0.26	0.33	0.68	0.38	0.60	0.77	0.89	1.42
75%	0.36	0.57	1.34	0.92	4.09	1.17	1.97	3.68
Burst duration (sec)
Mean	0.87	0.45	0.29	0.25	0.19	0.33	0.15	0.27
25%	0.56	0.29	0.17	0.08	0.11	0.11	0.08	0.08
50%	0.86	0.38	0.23	0.17	0.17	0.14	0.08	0.14
75%	1.24	0.59	0.32	0.32	0.29	0.20	0.14	0.23
Fano factor
Mean	18.10	9.04	7.74	4.48	6.00	7.37	2.63	6.93
25%	11.30	5.93	4.80	2.31	3.13	4.18	1.53	4.15
50%	15.10	8.49	6.69	4.27	5.09	6.50	2.38	5.72
75%	21.70	11.10	10.40	6.10	7.53	9.36	3.38	7.65
Interwave interval (sec)
Mean	72.23	58.56	109.83			141.03
25%	47.50	36.00	72.25			56.00
50%	64.00	47.00	91.50			92.00
75%	87.00	70.00	139.75			194.00
Wave speed (μm/sec)
Mean	199.80	273.90	NA			NA
SD	19.89	33.23	NA			NA
Correlation index intercept	69.04	10.12^a	6.92	5.65	3.16	5.43	1.84	2.46
		22.18^a
Half-maximum (μm)	151.67	275.06^a	246.67	276.15	387.23	301.50	570.96	465.51
		173.72^a

Non-normality of the firing rate, burst duration, and Fano factor distributions necessitated presentation of the quartiles [(1st-25%, 2nd-50% (median), 3rd-75%] of these distributions to more accurately represent the data. Wave speed was not calculated at P15 because no wavefront was easily discriminated. Interwave interval was not calculated at P21 or 6 weeks because waves were not present at these ages. The correlation index intercept is the value of the fitted exponential curve at the intercept with the y-axis; the half maximum is the distance over which the curve falls to half its initial value.
^aFor the correlation index parameters, the values for P11 (top) and P13 (bottom) are given separately.