Bipolar cells

Bipolar cells are the retinal interneurons that provide the principal pathway from photoreceptors (rod and cone cells) to ganglion cells. As well as transmitting signals directly from photoreceptors to ganglion cells they also connect to amacrine cells that help with the integration of information and with constructing an overview of the entire visual scene.

  • Bipolar cells are connected to the light sensitive rod and cone cells in the retina of the human eye.
  • There are around 12 types of bipolar cells and they all function as integrating centres.
  • Each type of bipolar cell acts as a specialised conduit for information about light collected by a single (or small group) of rod or cone cells.
  • Each type of bipolar cell transmits its own interpretation of information extracted from photoreceptors and passes this on to ganglion cells.
  • The output of bipolar cells to ganglion cells includes the direct response of the bipolar cell to signals derived from photo-transduction and also responses to signals received indirectly from information provided by amacrine cells.
  • We might imagine a type of bipolar cell that connects directly from a cone to a ganglion cell and simply passes on information about wavelength. The ganglion cell uses the information to determine whether a certain point is an observed scene is red or green.
  • Not all bipolar cells synapse directly with a single ganglion cell. Some channel information that is sampled by different sets of ganglion cells. Others terminate elsewhere within the complex lattices of interconnections within the retina enabling them to carry packets of information to an array of different locations and cell types.