Fig. 5.

Flies perform menotaxis to a sun stimulus and retain their heading preference over time. (A) Tethered flies were placed in a closed-loop LED flight arena and presented with a 2.3 deg bright spot or a 15 deg dark stripe. (B) When presented with a sun stimulus, an individual fly adopted a straight heading of 92 deg (dotted red line) within the first 90 s of flight. (C) A fly maintained a stripe frontally. (D) Population data are shown in polar plots, with each individual represented by a single line. Mean heading is indicated by angle and length represents vector strength. From left to right, plots show population responses to the sun stimulus, to a stripe or in the dark, with means and 95% confidence intervals in red. Points on the outside of each gray circle show a histogram of headings for all individuals. (E) Flies flew to the sun stimulus twice, with a gap of 5 min, 2 h or 6 h between flights. Plots show mean heading±circular variance, with variance multiplied by an arbitrary scale factor of 36 for visibility. The black diagonal line indicates perfect correspondence of headings in the first and second flight. The blue diagonal line shows where the second flight heading would be if heading were time compensated. Data are repeated on the ordinate to emphasize the circular nature of headings. Adapted from Giraldo et al. (2018).