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 acting directly to transmit signals from the photoreceptors to the ganglion cells.

  • Bipolar cells are connected to rod and cone cells by synapses.
  • There are around 12 types of bipolar cells and they all function as integrating centres.
  • Each type acts as a specialised conduit for information about light that has struck and single, or small group of rod and cone cells.
  • So, 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 onto ganglion cells includes the direct response of the bipolar cell to signals derived from phototransduction 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 compares signals on the basis of what is known of their wavelength. The ganglion cell uses the information to determine whether a certain point is a 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.