AII amacrine cells are a subtype of amacrine cells present in the retina of mammals. AII amacrine cell serve the critical role of transferring light signals from rod photoreceptors to the retinal ganglion cells (which contain the axons of the optic nerve)

The Classical Rod Pathway described the role of AII amacrine cells in the mammalian retina. This can be summarised as follows:[1][2]

  • In scotopic conditions, if a rod photoreceptor receives light in scotopic (dark) conditions, it will hyperpolarise.
  • The rod photoreceptor synapses with the rod bipolar cell.[note 1][note 2]
  • This rod bipolar cell will directly (exclusively) synapse with an AII amacrine cell in sublamina B (within the inner plexiform layer)[note 3]
  • The AII amacrine cells becomes activated (i.e., it depolarises) when light stimulates a rod.

(Once activated, the AII amacrine cell then modulates the cone ON and OFF channels):

  1. Other AII amacrine cells
  2. ON-cone bipolar cells

The ON- and OFF- cone bipolar cells in turn contact the ON- and OFF-centre retinal ganglion cells, respectively.

Note: A small proportion of rods contact the cone bipolar cells directly.

Footnotes

  1. There is only one type of rod bipolar cell: an ON-bipolar cell
  2. This is a 'sign-inverting' synapse.
  3. This is a 'sign-conserving' synapse.
  4. This is usually a reciprocal synapse

References


  1. Farsaii M, Connaughton VP (July 2011). "AII Amacrine Cells". webvision.med.utah.edu.
  2. Marc RE, Anderson JR, Jones BW, Sigulinsky CL, Lauritzen JS (4 September 2014). "The AII amacrine cell connectome: a dense network hub". Frontiers in Neural Circuits. 8: 104. doi:10.3389/fncir.2014.00104. PMC 4154443. PMID 25237297.
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