Understanding the circuit mechanisms behind motion detection is a long-standing question in visual neuroscience. In Drosophila melanogaster, recent synapse-level connectomes in the optic lobe, particularly in ON-pathway (T4) receptive-field circuits, in concert with physiological studies, suggest an increasingly intricate motion model compared with the ubiquitous Hassenstein-Reichardt model, while our knowledge of OFF-pathway (T5) has been incomplete. Here we present a conclusive and comprehensive connectome that for the first time integrates detailed connectivity information for inputs to both T4 and T5 pathways in a single EM dataset covering the entire optic lobe. With novel reconstruction methods using automated synapse prediction suited to such a large connectome, we successfully corroborate previous findings in the T4 pathway and comprehensively identify inputs and receptive fields for T5. While the two pathways are likely evolutionarily linked and indeed exhibit many similarities, we uncover interesting differences and interactions that may underlie their distinct functional properties.
The raw electron microscopy data, as well as skeletonized neurons and numbers of input and output synapses of T4 and T5 cells used in this study are hosted at a Janelia website: http://emdata.janelia.org/optic-lobe/.
- Stephen M Plaza
- Kazunori Shinomiya
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Alexander Borst, Max Planck Institute of Neurobiology, Germany
© 2019, Shinomiya et al.
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