The circadian clock in the retina controls rod-cone coupling

Neuron. 2008 Sep 11;59(5):790-801. doi: 10.1016/j.neuron.2008.07.017.


Although rod and cone photoreceptor cells in the vertebrate retina are anatomically connected or coupled by gap junctions, a type of electrical synapse, rod-cone electrical coupling is thought to be weak. Using tracer labeling and electrical recording in the goldfish retina and tracer labeling in the mouse retina, we show that the retinal circadian clock, and not the retinal response to the visual environment, controls the extent and strength of rod-cone coupling by activating dopamine D(2)-like receptors in the day, so that rod-cone coupling is weak during the day but remarkably robust at night. The results demonstrate that circadian control of rod-cone electrical coupling serves as a synaptic switch that allows cones to receive very dim light signals from rods at night, but not in the day. The increase in the strength and extent of rod-cone coupling at night may facilitate the detection of large dim objects.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptation, Ocular / physiology
  • Analysis of Variance
  • Animals
  • Circadian Rhythm / physiology*
  • Goldfish
  • Kinetics
  • Light
  • Lysine / analogs & derivatives
  • Lysine / metabolism
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Membrane Potentials / radiation effects
  • Mice
  • Mice, Inbred CBA
  • Patch-Clamp Techniques
  • Photic Stimulation / methods
  • Retina / physiology*
  • Retinal Cone Photoreceptor Cells / physiology*
  • Retinal Rod Photoreceptor Cells / physiology*
  • Sensory Thresholds / radiation effects
  • Spectrum Analysis
  • Visual Fields / physiology


  • biocytin
  • Lysine