What is it about?

Are olfactory neurons arranged in a functionally meaningful way to facilitate information processing? In this study, we identify a valence map in fly antennae and illustrate how lateral inhibition between neighboring olfactory receptor neurons mediates robust behavioral responses to countervailing cues.

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Why is it important?

A hallmark of complex sensory systems is the organization of neurons into functionally meaningful maps, such as retinotopic or somatotopic organizations, which allow for comparison and contrast of parallel inputs via lateral inhibition. In olfaction, however, both the existence and nature of such a sensory map remain undetermined, thus raising the central questions of whether and how chemosensory neurons are organized in a specific manner that impacts sensory processing. Here, we address these long-standing questions by uncovering a valence map in the olfactory periphery of Drosophila.


Dogma holds that olfactory coding follows a distributive model, whereby odor identities and hedonic values are both determined by the unique combinatorial activation patterns of olfactory receptor neurons (ORNs), the majority of which do not individually convey intrinsic valence. Here, our findings challenge this conventional view. Specifically, we reveal that most ORNs exhibit inherent hedonic values which, together with the valence-opponent organization of these neurons, allow countervailing cues to be swiftly processed in the periphery before sensory inputs are relayed to higher brain centers. Through this peripheral processing, opposing constituents in a complex odor mixture are no longer represented in their original proportions; rather, the salient cue is selectively transmitted to inform behavior. Thus, complex olfactory inputs are filtered for simplification at the first neurons of the sensory circuit.

Chih-Ying Su
University of California San Diego

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This page is a summary of: Valence opponency in peripheral olfactory processing, Proceedings of the National Academy of Sciences, January 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2120134119.
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