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Front. Neural Circuits | doi: 10.3389/fncir.2018.00103

Neuronal constituents and putative interactions within the Drosophila ellipsoid body neuropil

Jaison J. Omoto1, Bao-Chau M. Nguyen1, Pratyush Kandimalla1, Jennifer K. Lovick1,  Jeffrey M. Donlea1 and  Volker Hartenstein1*
  • 1Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, United States

The central complex (CX) is a midline-situated collection of neuropil compartments in the arthropod central brain, implicated in higher-order processes such as goal-directed navigation. Here, we provide a systematic genetic-neuroanatomical analysis of the ellipsoid body (EB), a compartment which represents a major afferent portal of the Drosophila CX. The neuropil volume of the EB, along with its prominent input compartment, called the bulb, is subdivided into precisely tessellated domains, distinguishable based on intensity of the global marker DN-cadherin. EB tangential elements (so-called ring neurons), most of which are derived from the DALv2 neuroblast lineage, interconnect the bulb and EB domains in a topographically-organized fashion. Using the DN-cadherin domains as a framework, we first characterized the bulb-EB connectivity by Gal4 driver lines expressed in different DALv2 ring neuron (R-neuron) subclasses. We identified 11 subclasses, 6 of which correspond to previously described projection patterns, and 5 novel patterns. These subclasses both spatially (based on EB innervation pattern) and numerically (cell counts) summate to the total EB volume and R-neuron cell number, suggesting that our compilation of R-neuron subclasses approaches completion. EB columnar elements, as well as non-DALv2 derived extrinsic ring neurons (ExR-neurons), were also incorporated into this anatomical framework. Finally, we addressed the connectivity between R-neurons and their targets, using the anterograde trans-synaptic labeling method, trans-Tango. This study demonstrates putative interactions of R-neuron subclasses and reveals general principles of information flow within the EB network. Our work will facilitate the generation and testing of hypotheses regarding circuit interactions within the EB and the rest of the CX.

Keywords: Drosophila, Ellipsoid body, central complex, neuroblast, Ring neurons, trans-Tango

Received: 02 Aug 2018; Accepted: 26 Oct 2018.

Edited by:

Claude Desplan, New York University, United States

Reviewed by:

Giorgio F. Gilestro, Imperial College London, United Kingdom
Makoto Sato, Kanazawa University, Japan  

Copyright: © 2018 Omoto, Nguyen, Kandimalla, Lovick, Donlea and Hartenstein. 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) and the copyright owner(s) 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: Prof. Volker Hartenstein, University of California, Los Angeles, Department of Molecular, Cell, and Developmental Biology, Los Angeles, United States, volkerh@mcdb.ucla.edu