Presentation Details
| Slow-acting peripheral inhibition underlies the behavioral dominance of aversive acidic odors Kay J.Ellison, Isaiah K.Asbed, James M.Jeanne. Yale University, New Haven, CT, USA |
Abstract
Animals often encounter environments containing multiple odors, yet how the nervous system prioritizes them to guide behavior remains poorly understood. Here, we identify a novel form of sensory dominance in Drosophila melanogaster in which aversive acidic odors hierarchically control behavioral choice. When forced to choose between equally aversive acidic and non-acidic odors, flies prefer to avoid the acidic odor. Notably, acidic odors override aversion to both innately aversive odors as well as odors rendered aversive through recent learning. This dominance emerges over tens of seconds and occurs only at acidic odor concentrations that are themselves innately aversive. Using in vivo calcium imaging, we show that acetic acid suppresses activity in olfactory receptor neurons (ORNs) expressing Orco, which encode non-acidic odors. This suppression occurs on the same slow timescale and with the same concentration-dependence as the behavioral dominance. Interestingly, suppression occurs in both the antenna and the antennal lobe, indicating that acid dominance is implemented within the sensory periphery. In contrast, non-acidic odors have no impact on activity in ORNs expressing Ir8a, which encode acidic odors. Suppression of Orco+ ORNs is propagated to downstream projection neurons, with inhibition in both populations closely matching the temporal dynamics of behavioral dominance. Together, these results reveal that hidden odor hierarchies can emerge during decision-making and can be implemented through asymmetric inhibition between peripheral sensory channels. This represents a previously unrecognized organizing principle in olfaction. Ecologically salient chemical cues can thus shape sensory priority at the earliest stages of the nervous system, prior to higher-order integration.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.