Current Biology
Volume 29, Issue 9, 6 May 2019, Pages 1545-1550.e2
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Extreme Compartmentalization in a Drosophila Amacrine Cell

https://doi.org/10.1016/j.cub.2019.03.070Get rights and content
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Highlights

  • Individual terminals of fly amacrine cell CT1 exhibit strong compartmentalization

  • Each CT1 terminal has a distinct visual receptive field

  • Biophysical modeling links morphology to signal compartmentalization

  • CT1 can thus support local motion detection

Summary

A neuron is conventionally regarded as a single processing unit. It receives input from one or several presynaptic cells, transforms these signals, and transmits one output signal to its postsynaptic partners. Exceptions exist: amacrine cells in the mammalian retina [1, 2, 3] or interneurons in the locust mesothoracic ganglion [4] are thought to represent many electrically isolated microcircuits within one neuron. An extreme case of such an amacrine cell has recently been described in the Drosophila visual system. This cell, called CT1, reaches into two neuropils of the optic lobe, where it visits each of 700 repetitive columns, thereby covering the whole visual field [5, 6]. Due to its unusual morphology, CT1 has been suspected to perform local computations [6, 7], but this has never been proven. Using 2-photon calcium imaging and visual stimulation, we find highly compartmentalized retinotopic response properties in neighboring terminals of CT1, with each terminal acting as an independent functional unit. Model simulations demonstrate that this extreme case of compartmentalization is at the biophysical limit of neural computation.

Keywords

Drosophila neurobiology
compartmental modeling
2-photon calcium-imaging
visual system
receptive field analysis
biophysics
motion detection

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