Encoding of luminance and contrast by linear and nonlinear synapses in the retina

Neuron. 2012 Feb 23;73(4):758-73. doi: 10.1016/j.neuron.2011.12.023.


Understanding how neural circuits transmit information is technically challenging because the neural code is contained in the activity of large numbers of neurons and synapses. Here, we use genetically encoded reporters to image synaptic transmission across a population of sensory neurons-bipolar cells in the retina of live zebrafish. We demonstrate that the luminance sensitivities of these synapses varies over 10(4) with a log-normal distribution. About half the synapses made by ON and OFF cells alter their polarity of transmission as a function of luminance to generate a triphasic tuning curve with distinct maxima and minima. These nonlinear synapses signal temporal contrast with greater sensitivity than linear ones. Triphasic tuning curves increase the dynamic range over which bipolar cells signal light and improve the efficiency with which luminance information is transmitted. The most efficient synapses signaled luminance using just 1 synaptic vesicle per second per distinguishable gray level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Calcium Signaling / genetics
  • Calcium Signaling / physiology
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Contrast Sensitivity / physiology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Embryo, Nonmammalian
  • Gene Expression Regulation, Developmental
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Light
  • Luminescence*
  • Models, Neurological*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Nonlinear Dynamics
  • Photic Stimulation
  • Pineal Gland / metabolism
  • Retina / cytology*
  • Sensory Receptor Cells / physiology*
  • Synapses / physiology*
  • Synaptic Transmission / genetics
  • Synaptic Transmission / physiology*
  • Zebrafish
  • Zebrafish Proteins / genetics
  • Zebrafish Proteins / metabolism


  • Carrier Proteins
  • DNA-Binding Proteins
  • Nerve Tissue Proteins
  • Sncaip protein, rat
  • Zebrafish Proteins
  • Green Fluorescent Proteins