A canonical motion detection algorithm in olfaction and its role in turbulent odor navigation
Sat-S14-003
Presented by: Nirag Kadakia
Insects navigate to odor sources by combining information from the intensity, timing, and spatial distribution of odor encounters. One key information stream is the difference in odor signals between the antennae. This bilaterally-resolved information enables gradient sensing, helping navigation in simple environments like static odor ribbons.
In turbulent plumes, however, gradients are of limited use since they are hard to resolve and carry little information about the source location. Here, we have discovered a distinct role for bilateral odor sensing—detecting the direction of motion of odors. This discovery was enabled by decoupling wind from odor using spatially and temporally precise optogenetic stimulation of freely-moving Drosophila. We used stimuli previously designed for visual motion detection studies, which decompose natural stimuli landscapes into their “building blocks” of spatiotemporal correlations.
Using this paradigm, we demonstrate that flies compute the direction of odor motion using a correlation-based algorithm equivalent to the Hassenstein-Reichardt correlator (HRC) proposed to describe motion detection in vision. Moreover, we replicated “olfactory illusions” providing direct evidence of correlation-based motion detection outside of vision. Finally, we combine computational modeling and virtual reality experiments to show that odor motion is a critical information stream in turbulent plumes enabling effective navigation to the source. Our work (1) reveals a critical role for bilaterality in olfaction; (2) shows that olfactory navigation exploits odor motion direction independent of wind direction; and (3) provides direct, causal evidence for analogous motion computations in olfaction and vision.
Funding provided by Swartz Foundation of Theoretical Neuroscience (USA), National Institutes of Health (USA), and National Science Foundation (USA)
In turbulent plumes, however, gradients are of limited use since they are hard to resolve and carry little information about the source location. Here, we have discovered a distinct role for bilateral odor sensing—detecting the direction of motion of odors. This discovery was enabled by decoupling wind from odor using spatially and temporally precise optogenetic stimulation of freely-moving Drosophila. We used stimuli previously designed for visual motion detection studies, which decompose natural stimuli landscapes into their “building blocks” of spatiotemporal correlations.
Using this paradigm, we demonstrate that flies compute the direction of odor motion using a correlation-based algorithm equivalent to the Hassenstein-Reichardt correlator (HRC) proposed to describe motion detection in vision. Moreover, we replicated “olfactory illusions” providing direct evidence of correlation-based motion detection outside of vision. Finally, we combine computational modeling and virtual reality experiments to show that odor motion is a critical information stream in turbulent plumes enabling effective navigation to the source. Our work (1) reveals a critical role for bilaterality in olfaction; (2) shows that olfactory navigation exploits odor motion direction independent of wind direction; and (3) provides direct, causal evidence for analogous motion computations in olfaction and vision.
Funding provided by Swartz Foundation of Theoretical Neuroscience (USA), National Institutes of Health (USA), and National Science Foundation (USA)