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. Author manuscript; available in PMC: 2009 Sep 1.
Published in final edited form as: Nat Neurosci. 2009 Feb 8;12(3):318–326. doi: 10.1038/nn.XXX

Figure 4.

Figure 4

Block of spike frequency adaptation has little effect on the time-course of looming response. (a) Responses to looming disks approaching with l/|v| = 10, 30 and 50 ms. Gaussian-convolved average instantaneous firing rate (inst. freq.) before (black) and after BAPTA iontophoresis (red). Envelopes indicate s.e.m. (5 locusts, 5 trials per locust per condition; N = 25). The bar plots depict the corresponding mean (〈f〉) and peak (fmax) firing frequencies (lines indicate s.e.m.; see Table 1). The BAPTA-induced change in fmax was significant only for l/|v| = 50 ms (P = 0.035), whereas the change in 〈f〉 was significant for l/|v| = 10 and 30 ms (P = 0.021 and 0.033, respectively). (b) Firing rate peak relative to collision time for the same three l/|v| values, before (black) and after (red) BAPTA. Solid lines indicate s.e.m. Dotted lines represent linear fits. Peak times after BAPTA shifted from 14.4 ± 3.1 ms (mean ± s.e.m.) to 19.3 ± 2.4 ms, 86.2 ± 17.9 ms to 94.8 ± 23.7 ms, and 265.1 ± 28.1 ms to 257.7 ± 29.3 ms for l/|v| = 10, 30 and 50 ms, respectively (P = 0.15, 1 and 1, respectively; N = 25). (c) Threshold angle (θthresh) as a function of delay to firing rate peak (δ). After BAPTA iontophoresis, θthresh shifted from 18.8° ± 1.7° to 19.9° ± 2.1° (P = 1, N = 25) and δ shifted from 66.1 ± 4.3 ms to 54.9 ± 4.1 ms (P = 0.1, N = 25). Same conventions as in b.