Presentation Details
| Receptor-defined lateral inhibition in the mammalian olfactory bulb Madison A.Herrboldt, Matt Wachowiak. University of Utah, Salt Lake Cty, UT, USA |
Abstract
Lateral inhibition plays a key role in shaping olfactory bulb output, yet its functional organization remains unclear. Inhibitory connections may be selectively structured by receptor identity or randomly distributed across the bulb, but testing these alternatives has been limited by the difficulty of mapping inhibitory inputs onto receptor-defined principal output neurons. To address this, we generated three odorant receptor (OR) tagged mouse lines in which olfactory sensory neurons (OSNs) expressing a specific OR co-express the fluorescent marker mKate2. These lines targeted one class I OR (Or52h2) and two class II ORs (Or10g9b and Or1ad1) and were crossed with mice expressing genetically encoded calcium indicators in either OSNs or mitral/tufted (MT) cells. We presented large odorant panels (40-50 odorants) to awake mice to characterize OSN and MT tuft tuning of tagged glomeruli. Excitatory tuning sharpened post-synaptically, and odorant-evoked suppressive responses also emerged. Odorants that suppressed Or52h2 dendritic tufts also suppressed daughter MT cell somata, indicating that suppressive glomerular signals reflect inhibition of olfactory bulb output. Notably, suppressive response spectra were stereotyped across animals, and odorants that activated class II OSNs did not suppress Or52h2 MT cells. This result appeared to generalize to other class I glomeruli. Moreover, suppression was overall less prevalent in MT tufts associated with the two class II glomeruli compared to the class I glomerulus. Together, these results support a receptor-defined rather than random inhibitory architecture and suggest that lateral inhibition in the olfactory bulb is heterogeneous across OR classes.
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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.
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