Table 1.

BAPTA produces a stronger increase in firing rate and longer sustained responses for translating stimuli than for looming stimuli

	fmax (spikes s−1)				〈f■〉, 〈f〉 (spikes s−1)				Longest contiguous time f > 50 spikes s−1 (ms)
Stimulus class	Control	BAPTA	Δ (%)	P-value	Control	BAPTA	Δ (%)	P-value	Control	BAPTA	P-value
Translating rectangles
10°× 10°, 40° s−1, A–P	32 ± 5	77 ± 10	144	7 ± 10−4	11 ± 1	44 ± 3	308	6 × 10−9	30 ± 6	397 ± 66	2 × 10−9
10° × 10°, 80° s−1, A–P	41 ± 7	81 ± 10	100	0.001	15 ± 2	52 ± 6	237	6 × 10−7	40 ± 7	353 ± 63	4 × 10−8
10° × 10°, 160° s−1, A–P	59 ± 6	93 ± 6	58	9 × 10−4	18 ± 2	58 ± 7	231	1 × 10−6	52 ± 8	260 ± 38	9 × 10−7
10° × 10°, 40° s−1, P–A	42 ± 5	92 ± 6	118	2 × 10−6	8 ± 1	31 ± 4	276	2 × 10−6	26 ± 6	213 ± 37	1 × 10−7
10° × 10°, 80° s−1, P–A	51 ± 4	100 ± 7	95	4 × 10−5	9 ± 2	42 ± 6	353	2 × 10−6	35 ± 6	217 ± 38	4 × 10−7
10° × 10°, 160° s−1, P–A	58 ± 5	102 ± 10	77	4 × 10−4	12 ± 2	46 ± 7	278	8 × 10−5	40 ± 6	128 ± 20	7 × 10−5
10° × 80°, 40° s−1, A–P	82 ± 9	137 ± 9	66	1 × 10−4	16 ± 2	52 ± 7	232	6 × 10−5	110 ± 16	651 ± 106	2 × 10−6
10° × 80°, 80° s−1, A–P	81 ± 10	122 ± 9	50	0.005	11 ± 2	33 ± 6	191	0.035	83 ± 14	282 ± 57	0.034
10° × 80°, 160° s−1, A–P	95 ± 10	130 ± 11	37	0.044	11 ± 2	18 ± 4	58	0.461	74 ± 7	140 ± 21	0.200
	Average		83				242
Looming disks
l/|v| = 10 ms	366 ± 50	541 ± 152	48	0.430	81 ± 7	116 ± 26	42	0.021	229 ± 14	245 ± 16	0.573
l/|v| = 30 ms	220 ± 32	236 ± 24	7	0.569	97 ± 9	114 ± 11	18	0.033	340 ± 26	375 ± 26	0.303
l/|v| = 50 ms	138 ± 16	211 ± 25	53	0.005	75 ± 8	112 ± 13	49	0.960	309 ± 33	306 ± 28	0.960
	Average		36				36

With the exception of the fastest-moving 10° × 80° rectangle, BAPTA produced significant increases for both maximal response frequency, f_max, and the mean response during the steady state period, 〈f_■〉, for all translating stimuli. The relative increase in looming response was much smaller and significant only for the weakest stimulus (l/|v| = 50 ms). The longest contiguous period of sustained firing above 50 spikes s⁻¹ was greatly increased for translating but not looming stimuli. All values are mean ± s.e.m. (N = 25 trials, pooled from 5 locusts with 5 trials each; Wilcoxon rank-sum test comparing the control (before BAPTA) with the response after BAPTA). Δ, percentage change of the mean after BAPTA treatment. The two average rows give mean relative changes across all translating and looming conditions, respectively. The raw data for looming and translating stimuli are shown in Figure 4 and Supplementary Figure 5, respectively.