The neural substrate of spectral preference in Drosophila

Neuron. 2008 Oct 23;60(2):328-42. doi: 10.1016/j.neuron.2008.08.010.

Abstract

Drosophila vision is mediated by inputs from three types of photoreceptor neurons; R1-R6 mediate achromatic motion detection, while R7 and R8 constitute two chromatic channels. Neural circuits for processing chromatic information are not known. Here, we identified the first-order interneurons downstream of the chromatic channels. Serial EM revealed that small-field projection neurons Tm5 and Tm9 receive direct synaptic input from R7 and R8, respectively, and indirect input from R1-R6, qualifying them to function as color-opponent neurons. Wide-field Dm8 amacrine neurons receive input from 13-16 UV-sensing R7s and provide output to projection neurons. Using a combinatorial expression system to manipulate activity in different neuron subtypes, we determined that Dm8 neurons are necessary and sufficient for flies to exhibit phototaxis toward ultraviolet instead of green light. We propose that Dm8 sacrifices spatial resolution for sensitivity by relaying signals from multiple R7s to projection neurons, which then provide output to higher visual centers.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amacrine Cells / cytology
  • Amacrine Cells / physiology
  • Amacrine Cells / radiation effects
  • Animals
  • Color Vision / physiology*
  • Color Vision / radiation effects
  • Compound Eye, Arthropod / cytology
  • Compound Eye, Arthropod / physiology*
  • Compound Eye, Arthropod / radiation effects
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / physiology*
  • Interneurons / cytology
  • Interneurons / physiology*
  • Interneurons / radiation effects
  • Light Signal Transduction / physiology
  • Light Signal Transduction / radiation effects
  • Optic Lobe, Nonmammalian / cytology
  • Optic Lobe, Nonmammalian / physiology
  • Photic Stimulation
  • Photoreceptor Cells, Invertebrate / cytology
  • Photoreceptor Cells, Invertebrate / physiology*
  • Photoreceptor Cells, Invertebrate / radiation effects
  • Synapses / physiology
  • Synapses / radiation effects
  • Synapses / ultrastructure
  • Synaptic Transmission / physiology
  • Synaptic Transmission / radiation effects
  • Ultraviolet Rays
  • Visual Pathways / cytology
  • Visual Pathways / physiology*
  • Visual Pathways / radiation effects