The Neuronal Basis of an Illusory Motion Percept Is Explained by Decorrelation of Parallel Motion Pathways

Curr Biol. 2018 Dec 3;28(23):3748-3762.e8. doi: 10.1016/j.cub.2018.10.007. Epub 2018 Nov 21.


Both vertebrates and invertebrates perceive illusory motion, known as "reverse-phi," in visual stimuli that contain sequential luminance increments and decrements. However, increment (ON) and decrement (OFF) signals are initially processed by separate visual neurons, and parallel elementary motion detectors downstream respond selectively to the motion of light or dark edges, often termed ON- and OFF-edges. It remains unknown how and where ON and OFF signals combine to generate reverse-phi motion signals. Here, we show that each of Drosophila's elementary motion detectors encodes motion by combining both ON and OFF signals. Their pattern of responses reflects combinations of increments and decrements that co-occur in natural motion, serving to decorrelate their outputs. These results suggest that the general principle of signal decorrelation drives the functional specialization of parallel motion detection channels, including their selectivity for moving light or dark edges.

Keywords: Drosophila; ON and OFF channels; decorrelation; direction selectivity; elementary motion detectors; illusory motion; natural scenes; natural statistics; parallel pathways; reverse-phi.

Publication types

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

MeSH terms

  • Animals
  • Drosophila melanogaster / physiology*
  • Female
  • Illusions / physiology*
  • Motion Perception / physiology*
  • Neural Pathways*
  • Neurons / physiology*