Extended Data Fig. 2. Silencing of either DNp02 or DNp11 impairs control of postural shifting and takeoff direction in response to looming stimuli.
For neuronal silencing experiments, driver lines for DNp02, DNp11, and an ‘Empty’ driver line control were crossed into UAS-Kir2.1. a–b, Polar takeoff direction histograms in response to looming stimuli presented in front of the fly at 0° azimuth (a) or behind the fly at 180° azimuth (b); 12° bin width; red line, mean resultant vector. DN-silenced flies perform normally in response to a posterior (180°) stimulus compared to control (p > 0.1 for both DNs, Kuiper’s Test). However, DN silencing altered the distribution of backward takeoffs direction in response to frontal looming (0°) for both DNp02 (p < 0.005, Kuiper’s test) and DNp11 (p < 0.001, Kuiper’s test) silencing compared to controls. Strikingly, many DNp02- and DNp11-silenced flies performed forward takeoffs in response to frontal looming stimulation, effectively jumping toward the threatening stimulus. c, To further understand why flies were inappropriately taking off forwards, we looked at how much DN-silenced flies moved their COM backwards in response to 0° looming. We visualized COM movement in body coordinates from different starting postures using the same flow fields in body-centric coordinates as in Extended Data Fig. 1d. Visual inspection indicated that COM movement fields for DN-silenced flies differed from controls in the amount of backwards movement and had more lateral movement. d, To quantify this motion, we measure the T2 angle (angle formed by T2 tarsal contact points and COM), which is >180° when the COM is in front of the T2 jumping legs and <180° when the COM is behind the T2 jumping legs. The mean T2 angle just before takeoff was significantly different for DNp02- and DNp11-silenced flies compared to controls (*p = 0.0468, ***p = 4.79e-04, One-Way ANOVA, Dunnett’s test). Black points, individual flies; error bars, SD. e, Looking at time courses for T2 leg angle in response to 0° azimuth looming stimulus for the different DN-silenced lines (colors, shaded area, SD), with control data overlaid (grey), it is clear that the difference in the DN-silenced flies is that they do not shift backwards as much as controls. Since COM placement prior to takeoff determines whether the fly’s jump will propel it forwards (T2 angle>180) or backwards (T2 angle<180), the impaired pre-takeoff T2 leg angle change in DNp02- and DNp11-silenced flies, which on average does not become <180° as in control flies, likely underlies altered takeoff performance leading to more forward-directed takeoffs. f, DNp02 and DNp11 silencing does not affect takeoff rates. Percentage of flies which performed a takeoff to a looming visual stimulus (azimuth = 90°, elevation = 45°) at four looming rates (l/v = 10, 20, 40 and 80 ms), or a looming visual stimulus (azimuth = 0° or 180°, elevation = 45°) at l/v = 40. L1/L2-silenced flies serve as “motion-blind” negative controls. Error bars, SEM; Wilson score interval; **p < 0.01, ***p < 0.001, ****p < 0.0001 versus Empty control; normal approximation to binomial, two-sided Z-test, Bonferroni correction post hoc test. Detailed description of statistical tests and p-values for panel “f” is available in Supplementary Table 1.