High fidelity transmission of temporal stimulus cues in the insect olfactory system

Abstract

Insects primarily rely on olfaction to locate resources such as food or mating partners. Tracking down an odor source poses a particular challenge: small scale air dynamics cause odors to occur in turbulent plumes in which they intermingle among themselves and with background odors, creating temporally complex patterns of different concentrations and odor mixtures. How do insects detect, recognize and find the right odor source in such a complicated odor environment? Odorants from the same sources fluctuate synchronously, whereas odorants from spatially separated sources fluctuate asynchronously. I will present evidence that the insect olfactory system is capable to resolve fast odor plume dynamics, which would allow it to detect whether odorants originate from the same or separate sources. Extracellular recordings from Drosophila olfactory receptor neurons show that (1) they can respond to odorants within less than 3 milliseconds (they are fast), and (2) follow repetitive odorant pulses above 100 Hz (they have high temporal resolution). Calcium imaging in the honey bee antennal lobe shows that projection neurons can resolve few millisecond asynchrony in the arrival of two odorants. Correspondingly, behavioral experiments in honey bees show that few millisecond asynchrony between odorants facilitates the perceptual segregation of concurrent odorants. These data show that temporal jitter between stimuli may help telling odor objects apart. Thus, olfactory source segregation shares common principles with visual and auditory source segregation in humans: we also use temporal jitter between stimuli to tell objects apart.