Figure 4. Optogenetically induced virtual local search in a tethered fly.

(A) Schematic of virtual reality system to study path integration in a tethered fly. The fly walks on an air-suspended spherical treadmill, and its fictive path is reconstructed in real-time using an overhead camera and FicTrac machine vision software [61]. A closed-loop program presents fictive food sites in the virtual 2-D environment by controlling optogenetic activation of Gr43a-GAL4 sugar-sensing neurons.

(B) Longest distance search bouts (from left to right, plotted as in Figure 1C). Outer ring represents virtual arena edge.

(C) Mean number of revisits to the activation zone during search bouts for Gr43a-GAL4>UAS-CsChrimson animals (n=18) or GAL4 parental control animals (n=13), plotted as in Figure 1I. Trials included two 10-minute control periods during which animals received no optogenetic stimulation: an initial baseline period (blue) and a final post-experimental period (grey). Unfilled circles indicate that the median is statistically different from both baseline and post-experimental condition (Wilcoxon signed-rank test, p≤0.05, with Bonferroni correction).

(D) Mean distance walked during search bouts, plotted as in Figure 1J, statistics as in (C).

(E) Centers of mass for all activation search bouts, plotted as in Figure 1F. (F) Median speed traces during light pulse stimulation for animals of the indicated genotype, plotted as in Figure S4B.