Origin and functional impact of dark noise in retinal cones

Neuron. 2000 Apr;26(1):181-6. doi: 10.1016/s0896-6273(00)81148-4.


Spontaneous fluctuations in the electrical signals of the retina's photoreceptors impose a fundamental limit on visual sensitivity. While noise in the rods has been studied extensively, relatively little is known about the noise of cones. We show that the origin of the dark noise in salamander cones varies with cone type. Most of the noise in long wavelength-sensitive (L) cones arose from spontaneous activation of the photopigment, which is a million-fold less stable than the rod photopigment rhodopsin. Most of the noise in short wavelength-sensitive (S) cones arose in a later stage of the transduction cascade, as the photopigment was relatively stable. Spontaneous pigment activation effectively light adapted L cones in darkness, causing them to have a smaller and briefer dim flash response than S cones.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Darkness*
  • Guanosine Triphosphate / pharmacology
  • Phosphoric Diester Hydrolases / drug effects
  • Phosphoric Diester Hydrolases / metabolism
  • Retinal Cone Photoreceptor Cells / physiology*
  • Urodela
  • Vision, Ocular / drug effects
  • Vision, Ocular / physiology*


  • Guanosine Triphosphate
  • Phosphoric Diester Hydrolases