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First published online November 17, 2006
Journal of Experimental Biology 209, 4597-4606 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02583
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A comparison of visual and haltere-mediated feedback in the control of body saccades in Drosophila melanogaster

John A. Bender* and Michael H. Dickinson

Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA


Figure 1
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  		Fig. 1. Experimental design. (A) Fly orientation was determined at 564 Hz by a near-IR camera and custom software, which was used to modify the visual stimulation presented on a 32x64 cylindrical array of LEDs. N, magnetic north; S, south. (B) Flies were glued to a steel pin, which was placed in a magnetic field such that they could rotate only about their functional yaw axis. (C) Manipulation of visual feedback during saccades. When the realtime software detected the initiation of a saccade, the striped visual stimulus was rotated by 40° in 80 ms (gray box). The blue trace shows the fly's observed orientation; the green trace shows the angular position of the striped pattern. (D) Post hoc calculation of saccade dynamics. Saccade duration was the time during which the fly's angular velocity exceeded one-quarter of its maximum value during the saccade. Saccade amplitude was the difference between the median of the orientation measurements taken in the 50 ms immediately before and after the saccade.

 

Figure 2
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  		Fig. 2. (A) The rotational gain (classic optomotor response) of flies in a rotating drum featuring vertical stripes. Gain was calculated as the mean angular velocity of the fly divided by the angular velocity of the pattern during a single trial. Values are means ± s.e.m. across all trials, where each trial consisted of 10 s of rotation with a given stripe width. N=4 flies, n=[123, 123, 123, 125, 130] trials. Stripe widths tested correspond to 1-5 pixels in our visual arena. (B) Error between real-time and post hoc saccade detection timing. Only events during which the real-time software detected a saccade within 15 ms after its true initiation time as calculated post hoc (gray box) were included for further analysis.

 

Figure 3
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  		Fig. 3. Artificial visual rotation during saccades does not affect saccade dynamics (amplitude, duration or peak angular velocity). Flies performed spontaneous saccades in a visual panorama displaying a 45° dark stripe in the foreground (represented here in light gray for clarity) over a background of thin vertical stripes with a spatial frequency of 22.5°. When a fly began a saccade, either the foreground or background was rotated by a predetermined amount. Top to bottom: no visual rotation (control, n=134 saccades); foreground rotated with fly's turn (n=151); foreground rotated against fly's turn (n=148); background with (n=163); background against (n=142). Most of the distributions (here and in other figures) are neither normal nor lognormal (Shapiro-Wilk test, W<0.05); therefore, pink bars show the median value. None of the distributions here differed significantly from the control (Kruskal-Wallis nonparametric one-way ANOVA with Bonferroni correction for multiple comparisons, P>0.05). N=14 flies.

 

Figure 4
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  		Fig. 4. Vision plays only a minor role in modulating saccade dynamics, independent of wing aerodynamics. Top row: lights on; bottom row: lights off. (A) Saccade absolute amplitude, (B) duration, (C) peak absolute velocity. N=7 intact flies (n=726 light, n=629 dark saccades), N=3 clipped (n=308 light, n=586 dark saccades). Statistical analysis was as in Fig. 3 (*P<0.001; **P<0.02).

 

Figure 5
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  		Fig. 5. Modifying haltere feedback changes saccade dynamics. (A) The halteres. (B) Angular rotations of the fly's body cause the halteres to be deflected out of their stroke plane by Coriolis forces. In our preparation, these forces are proportional to the fly's angular velocity about its yaw axis ({omega}) and the halteres' mass (m) and velocity (v). The deflections caused by the Coriolis forces are sensed by haltere mechanoreceptors. (C) Changing the amount of haltere feedback affects saccade dynamics. Top to bottom: control (same data as top row of Fig. 3, N=14 flies, n=134 saccades); haltere feedback increased by adding mass to the haltere endknobs (N=6, n=113); haltere feedback decreased by ablating left haltere (N=5, n=121). Statistical analysis was as in Fig. 3 (*P<0.001).

 

Figure 6
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  		Fig. 6. No crossmodal effects were observed of visual feedback and haltere-mediated feedback, or visual feedback and aerodynamic modification, during saccades. Top to bottom: no visual rotation (control); foreground with/background with; foreground against/background against. (A) Halteres weighted (N=6 flies, top to bottom n=[113, 130, 137] saccades); (B) left haltere ablated (N=5, n=[121, 187, 121]); (C) posterior of wing ablated (N=5, n=[110, 136, 110]). Statistical analysis was as in Fig. 3 (P>0.05).

 

Figure 7
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  		Fig. 7. Altering wing aerodynamics affects saccade dynamics. Top to bottom: control (same data as top row of Fig. 3; N=14 flies, n=134 saccades); posterior half of right wing removed (N=5, n=110); distal third of left wing removed (N=5, n=1292 for statistical purposes, although only 150 randomly selected saccades are plotted). Statistical analysis was as in Fig. 3 (*P<0.001; **P<0.02).

 

Figure 8
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  		Fig. 8. Changes in saccade dynamics are laterally symmetric in asymmetrical preparations. Statistical analysis was as in Fig. 3, using leftward saccades as the control condition (P>0.05).

 

Figure 9
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  		Fig. 9. Both intact and wing-clipped flies stabilize orientation using visual feedback. (A,B) Characteristic traces from the entire recording session of (A) an intact fly and (B) a fly in which the posterior half of the right wing was removed. Black: angular velocity, lowpass filtered at 0.1 Hz; blue: orientation. Gray boxes denote periods when the arena lights were turned off (1 min off, 1 min on). (C,F) Angular velocity histograms from all flies tested (C: intact; F: clipped). Top row: lights on; bottom row: lights off. (D) Standard deviations of the distributions in C and F. (E) Each bar shows the mean of the absolute values of all the velocity measurements taken in that condition. N=7 intact flies, N=3 clipped; n=157024 intact-light samples, n=175648 intact-dark, n=59532 clipped-light, n=63265 clipped-dark.

 

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© The Company of Biologists Ltd 2006