A novel signaling pathway from rod photoreceptors to ganglion cells in mammalian retina

Neuron. 1998 Sep;21(3):481-93. doi: 10.1016/s0896-6273(00)80560-7.


Current understanding suggests that mammalian rod photoreceptors connect only to an ON-type bipolar cell. This rod-specific bipolar cell excites the All amacrine cell, which makes connections to cone-specific bipolar cells of both ON and OFF type; these, in turn, synapse with ganglion cells. Recent work on rabbit retina has shown that rod signals can also reach ganglion cells without passing through the rod bipolar cell. This route was thought to be provided by electrical gap junctions, through which rods signal directly to cones and thence to cone bipolar cells. Here, we show that the mouse retina also provides a rod pathway bypassing the rod bipolar cell, suggesting that this is a common feature in mammals. However, this alternative pathway does not require cone photoreceptors; it is perfectly intact in a transgenic mouse whose retina lacks cones. Instead, the results can be explained if rods connect directly to OFF bipolar cells.

Publication types

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

MeSH terms

  • Aminobutyrates / pharmacology
  • Animals
  • Darkness
  • Excitatory Amino Acid Agonists / pharmacology
  • Eye Proteins / genetics
  • Eye Proteins / physiology
  • Female
  • Humans
  • In Vitro Techniques
  • Light
  • Mammals
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Models, Biological
  • Photic Stimulation
  • Rabbits
  • Retinal Cone Photoreceptor Cells / drug effects
  • Retinal Cone Photoreceptor Cells / physiology*
  • Retinal Ganglion Cells / physiology*
  • Retinal Pigments / genetics
  • Retinal Pigments / physiology
  • Retinal Rod Photoreceptor Cells / drug effects
  • Retinal Rod Photoreceptor Cells / physiology*
  • Rod Opsins
  • Signal Transduction* / drug effects
  • Strychnine / pharmacology
  • Synapses / drug effects
  • Synapses / physiology


  • Aminobutyrates
  • Excitatory Amino Acid Agonists
  • Eye Proteins
  • Retinal Pigments
  • Rod Opsins
  • long-wavelength opsin
  • 2-amino-4-phosphonobutyric acid
  • Strychnine