Dynamic nonlinearities enable direction opponency in Drosophila elementary motion detectors
Authors: Damon A Clark
Jacob A Zavatone-Veth
Bara A Badwan
Matthew S Creamer
Journal: Nature Neuroscience (2019)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Direction-selective neurons; direction opponency; Drosophila; motion detectors; feedforward computations
Affiliations: School of Engineering and Applied Science, Yale University, New Haven, CT, USA., Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA., Department of Physics, Yale University, New Haven, CT, USA., Interdepartmental Neuroscience Program, Yale University, New Haven, CT, USA. ., Department of Physics, Yale University, New Haven, CT, USA. ., Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA. ., Department of Neuroscience, Yale University, New Haven, CT, USA. .

Abstract:  Direction-selective neurons respond to visual motion in a preferred direction. They are direction-opponent if they are also inhibited by motion in the opposite direction. In flies and vertebrates, direction opponency has been observed in second-order direction-selective neurons, which achieve this opponency by subtracting signals from first-order direction-selective cells with opposite directional tunings. Here, we report direction opponency in Drosophila that emerges in first-order direction-selective neurons, the elementary motion detectors T4 and T5. This opponency persists when synaptic output from these cells is blocked, suggesting that it arises from feedforward, not feedback, computations. These observations exclude a broad class of linear-nonlinear models that have been proposed to describe direction-selective computations. However, they are consistent with models that include dynamic nonlinearities. Simulations of opponent models suggest that direction opponency in first-order motion detectors improves motion discriminability by suppressing noise generated by the local structure of natural scenes. 

Retracted: No

PubPeer comments:
  Moving scenes generally include local motion that is oriented differently from the motion of the entire scene (Adelson Movshon (1982). Cells that respond to the local directed motion are termed component selective, whereas those that respond to the direction of the larger scene are termed pattern selective. The Adelson Movshon (1982) reference needs to be retired; it was [never valid] , as it started from a premise that could be shown to be false based on the very reference (Wallach, 1935) they use to support it. The field still coasts on such demonstrably false premises. u201cT4 and T5 cells are local motion detectors with small fields of view.u201d It is known that perceived motion, just like perceived form, is constructed on the basis of extended areas. Distal motion cannot be inferred on the basis of local retinal events. This is just a fact of logic and experiment. This is why Badwan et al s references to u201clocal motion detectorsu201d and motion  signals,u201d as in the excerpt below, are simply uninformed: u201cThese simulations suggest that opponency in the earliest stages of motion detection...Thus, direction opponency in first-order DS neurons may improve the fidelity of motion coding in local motion detectors and in downstream circuits that receive their signals.u201d Fortunately, I guess, contemporary neuroscience, with its unconstrained paper  models and [correlation-fished  data, ] has long immunized itself from the lethal effects of the facts. ,