Visualizing retinotopic half-wave rectified input to the motion detection circuitry of Drosophila

Nat Neurosci. 2010 Aug;13(8):973-8. doi: 10.1038/nn.2595. Epub 2010 Jul 11.


In the visual system of Drosophila, photoreceptors R1-R6 relay achromatic brightness information to five parallel pathways. Two of them, the lamina monopolar cells L1 and L2, represent the major input lines to the motion detection circuitry. We devised a new method for optical recording of visually evoked changes in intracellular Ca2+ in neurons using targeted expression of a genetically encoded Ca2+ indicator. Ca2+ in single terminals of L2 neurons in the medulla carried no information about the direction of motion. However, we found that brightness decrements (light-OFF) induced a strong increase in intracellular Ca2+ but brightness increments (light-ON) induced only small changes, suggesting that half-wave rectification of the input signal occurs. Thus, L2 predominantly transmits brightness decrements to downstream circuits that then compute the direction of image motion.

MeSH terms

  • Animals
  • Calcium / metabolism
  • Drosophila
  • Evoked Potentials, Visual / physiology
  • Motion Perception / physiology*
  • Photic Stimulation
  • Photoreceptor Cells / cytology
  • Photoreceptor Cells / physiology*
  • Visual Pathways / cytology
  • Visual Pathways / physiology*


  • Calcium