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ORIGINAL RESEARCH article

Front. Physiol.
Sec. Invertebrate Physiology
Volume 15 - 2024 | doi: 10.3389/fphys.2024.1410946
This article is part of the Research Topic Invertebrate brains as model systems for learning, memory, and recall: development, anatomy and function of memory systems View all 7 articles

Modeling and Characterization of Pure and Odorant Mixture Processing in the Mushroom Body Calyx

Provisionally accepted
Aurel A. Lazar Aurel A. Lazar 1*Tingkai Liu Tingkai Liu 1Chung-Heng Yeh Chung-Heng Yeh 1Yiyin Zhou Yiyin Zhou 2
  • 1 Columbia University, New York City, New York, United States
  • 2 Fordham University, New York City, United States

The final, formatted version of the article will be published soon.

    Associative memory in the Mushroom Body of the fruit fly brain depends on the encoding and processing of odorants in the first three stages of the Early Olfactory System: the Antenna, the Antennal Lobe and the Mushroom Body Calyx. The Kenyon Cells (KCs) of the Calyx provide the Mushroom Body compartments the identity of pure and odorant mixtures encoded as a train of spikes. Characterizing the code underlying the KC spike trains is a major challenge in neuroscience. To address this challenge we start by explicitly modeling the space of odorants using constructs of both semantic and syntactic information. Odorant semantics concerns the identity of odorants while odorant syntactics pertains to their concentration amplitude. These odorant attributes are multiplicatively coupled in the process of olfactory transduction. A key question that early olfactory systems must address is how to disentangle the odorant semantic information from the odorant syntactic information. To address this problem we devised an Odorant Encoding Machine (OEM) modeling the first three stages of early olfactory processing in the fruit fly brain. Each processing stage is modeled by Divisive Normalization Processors (DNPs). DNPs are spatio-temporal models of canonical computation of brain circuits. The end-to-end OEM is constructed as cascaded DNPs. By extensively modeling and characterizing the processing of pure and odorant mixtures in the Calyx, we seek to answer the question of its functional significance. We demonstrate that the DNP circuits in the OEM combinedly reduce the variability of the Calyx response to odorant concentration, thereby separating odorant semantic information from syntactic information. We then advance a code, called first spike sequence code, that the KCs make available at the output of the Calyx. We show that the semantics of odorants can be represented by this code in the spike domain and is ready for easy memory access in the Mushroom Body compartments.

    Keywords: Drosophila, Olfaction, divisive normalization, Calyx, APL, Kenyon cell, Odorant mixture

    Received: 02 Apr 2024; Accepted: 05 Sep 2024.

    Copyright: © 2024 Lazar, Liu, Yeh and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Aurel A. Lazar, Columbia University, New York City, 10027, New York, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.