Figure 6. Odor direction sensing enhances naturalistic plume navigation.

a, Snapshot of simulation of plume from Fig. 1. Grey arrows: wind direction at snapshot instant. b, left column: Odor velocity (colors) and wind (grey) vectors at snapshot instant, at boxed locations in a. Middle and right column: Distributions of same over whole simulation. c, Top: Mean odor velocity field. Bottom: Mean wind field for detectable odor concentrations. d, Illustration of fictive odor “plume” in which 2 mm-wide bars move outward or inward from arena centerline at 15 mm/s. Laminar wind flows at 150 mm/s. e, Measured fly tracks for flies beginning in the downwind 50 mm end of the arena, for outward (left) or inward (right) bars. Black tracks: flies that reached a 50 mm box around the fictive plume source. f, Left: Flies in outward bar plume were more likely to reach the source: 56% (28/50 tracks) vs. 28% (12/43 tracks) (p=1.13e-3, one-tailed t-test). Middle and right: Distributions of flies’ lateral (y) position, in the downwind (left) or upwind (right) end of the arena, respectively. g, Projected complex plume, played either normally or in reverse. h-i Analog of e-f. Flies in normal playback were more likely to reach the source: 32% (22/69 tracks) vs. 14% (13/91 tracks) (p=6.39e-3, one-tailed t-test). j, Simulated agent model based on Drosophila odor navigation¹⁰. Non-direction-selective (DS-) agents increase the upwind bias of stochastic left/right turns with odor hit frequency (top; green). Direction-selective (DS+) agents turn against the vector sum of the wind and odor directions as hit frequency increases (bottom; purple). k, Tracks of DS+ (left) and DS- (right) agents navigating complex plume in g. l, Analogue of f and i. DS+ agents were more likely to reach source (34% vs. 25%, p = 9.98e-5; 1-tailed t-test).