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. Author manuscript; available in PMC: 2016 Jun 1.
Published in final edited form as: Curr Biol. 2015 May 7;25(11):1526–1534. doi: 10.1016/j.cub.2015.04.025

Figure 3. Spiral fiber neurons are necessary for lateralized M-cell mediated escapes.

Figure 3

A. Tail free larvae are presented with a non-directional tap stimulus as in Figure 2.

B. Projection of two-photon image stack showing M-cells before (top image) and 24 hours after (bottom image) ablation of the M-cell on the left in Et(fos:Gal4-VP16)s1181t; Tg(UAS:Kaede).

C. Projection of two-photon image stack showing spiral fiber neurons before (top image) and 24 hours after (bottom image) ablation of spiral fiber neuron somata located on the right in Tg(-6.7FRhcrtR:gal4VP16); Tg(UAS:Kaede). The axon cap (green oval) contralateral to the targeted spiral fiber neurons is no longer apparent 24 hours after ablations.

D. Normalized change in short-latency (SL) escape probability as a function of all trials (post-pre/post+pre). Individual fish (grey circles) and median (black line). Left: M-cell ablation (n = 11). Right: spiral fiber neuron ablations (n = 17). The probability change is not significantly different from 0 in either condition (p = 0.67 and 0.98 respectively, Wilcoxon signed rank test).

E. Model showing that when M-cells or spiral fiber neurons are ablated unilaterally, escapes in response to taps become strongly biased towards one direction: ipsilateral to the ablated M-cell or contralateral to the ablated spiral fiber neurons.

F. Example tail traces for a fish before (top plots, black) and after (bottom plots, red) ablation of the left M-cell (left plots) and a fish before and after ablations of spiral fiber neuron somata on the right (right plots). The directionality of the initial tail bend is expressed as ipsilateral (ipsi) or contralateral (contra) with respect to the ablated soma(ta). Traces begin at the time of tap delivery.

G. Probability of contralateral SL escapes as a function of all SL escapes of either direction. Left panel: M-cell ablation. Right panel: spiral fiber neuron ablations. Escapes shift toward the ipsilateral side for M-cell ablation, and to the contralateral side for spiral fiber neuron ablations. The laterality bias following M-cell or spiral fiber neuron ablation was not statistically distinguishable (p = 0.45, Wilcoxon rank sum test).

Scale bars: 20 μm. Pictures are oriented rostral up. Abbreviations: SF: spiral fiber; LS: short-latency; contra: contralateral; ipsi: ipsilateral.