On Midget Ganglion Cell

References

There appears to be a further subcategory for the on midget ganglion cell. Calkins et al, provide anatomical evidence which suggests that one can discriminate between midget ganglion cells by the class of cone it receives input from. Unfortunately, it is not possible to firmly label one class as red/long and the other as green/medium. So, I distinguish between the two categories using the Calkins PhD terminology of small for the ganglion with fewer synapses and large for the ganglion cell with more synapses.

For a patch of 94 cone-midget ganglion circuits, 59 were large circuits and 45 were small circuits (a ratio of 1.3).

It is suggested that midget ganglion cells provide from 80% to 95% of the ganglion cell poplulation.

• Postsynaptic connections (Input) -Diagram

  The midget bipolar receives input in a dyad formation: a single bipolar synapse provides input to two distinct dendrites. The midget ganglion shares the dyad with an amacrine 87% of the time. For further details see the midget bipolar page.

  • Invaginating On Midget Bipolar
    • Small: 28 +-4 synapses from a single invaginating midget bipolar
    • Large: 47 +-3 synapses from a single invaginating midget bipolar
    • This synapse occurs in the lower/deep/sublamina b part of the Inner Plexiform Layer.
  • Unclassified Amacrine
    • Each midget ganglion cell receives approximately the same number of midget bipolar and amacrine inputs.
    • Small: 30+-3 synapses from unclassified amacrine cell(s)
    • Large: 45+-3 synapses from unclassified amacrine cell(s)
  • Diffuse bipolar cell
    • "Occasionally, a midget ganglion cell receives a synapse from a diffuse bipolar cell terminal.

• Presynaptic connections (Output)
  • Lateral Geniculate Nucleus Parvocellular layer

• Function

• Morphology
  • Small dendrites: 81 +-7 micrometers2 of membrane surface
  • Large dendrites: 105 +-23 micrometers2 of membrane surface

• Array characteristics

• Compartmental Model Characteristics

• Location

• Subclasses

• Synapse types
  • Post-synaptic synapse (Input)
    • An excitatory glutamatergic bipolar synapse.
  • Pre-synaptic synapse (Output)

• Synapse Receptors
  • Glutamate receptors

• Neurotransmitters
  • Glutamate excites

• Immunoreactivity

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