Amacrine AII

• Dopaminergic Amacrine cells
  • This input has been described as Massive.
• Rod Bipolar
  • 28 Rod Bipolars
• Cone bipolar cells
  • Cohen and Sterling, 1990
    • cb5/B1 via electrical synapses
    • cb6/B2 via electrical synapses
    • B4 via electrical synapses
  • McGuire, Stevens and Sterling, 1984
    • cb1 via a chemical synapses
    • cb2 via a chemical synapses
    • CBa3 (not cb3) via a chemical synapses
    • rod bipolar via a chemical synapses
  • AII Amacrines
    • 2 or 3 AII Amacrines via electrical synapses
  • A18 Amacrines

• Presynaptic connections (Output)
  • Off Ganglion Cells
    • Chemical synapses in sublamina a of the inner plexiform layer
  • Cone bipolar
    • electrical synapses onto cone bipolar axons in sublamina b of the inner plexiform layer
  • On Ganglion Cells
    • Contacts made via electrical synapses onto cone bipolar axons in sublamina b
    • Off- Beta/X Ganglion Cell (Kolb and Nelson, '93)
  • AII Amacrines
    • 2 or 3 AII Amacrines via electrical synapses

• Function
  • Rod-dominated Light depolarizes the AII. (Nelson, 1982; Dacheux and Raviola, 1986; Bloomfield, 1992)
  • Vaney (1994)
    • Likely inhibitory output because they accumulate glycine
    • "...coupling between AII cells is probably strongest under scotopic conditions, when the release of endogenous dopamine is minimal."

• Morphology
  • A stout stalk descends through the inner plexiform layer
  • Spacing is about 16 micrometers
  • Density in cat : 3300/mm2 Vardi & Smith
  • : 4100-5300/mm2 Vaney, 1985 & Sterling et al. 1988
  • Large gap junctions when AII somas are next to each other
  • Small gap junctions on distal processes away from the soma.
  • Average gap junction between AII was .8micrometer2
  • Vaney '90
    • lobular dendrites
    • Bilaminar: 1 lamina in sublamina a (s1,s2) and the other in sublamina b (s3-s5) IPL (Vaney, 1990)
  • Pourcho and Goebel, 1985
    • lobular dendrites in sublamina a of the IPL
    • fine dendrites in sublamina b of the IPL

• Array characteristics
  • Cells are coupled via gap junctions. The extent of coupling appears to be decreased by dopamine from dopaminergic amacrines. Vaney (1994)

• Compartmental Model Characteristics

• Location
  • Vaney (1994)
    • "In sublamina a of the IPL, the soma and thick primary dendrites give rise to fine processes that terminate in varicose endings termed 'lobular appendages'"
    • "In sublamina b (IPL), the primary dendrites branch repeatedly to form conical arborization that is wider than the lobular field."

• Subclasses

• Synapse types
  • Voltage-gated channels

• Synapse Receptors

• Neurotransmitters
  • glycinergic - lightly labeled (Pourcho and Goebel, 1985)
  • dopamine suppresses AII coupling
  • D1 dopamine receptors are in AII arbors in the rat (Veruki, Derouiche an Wassle '96 ARVO)

• Immunoreactivity
  • fluorescent molecule 4,6-diamidino-2-phenylindole (DAPI) - Vaney, '85

• Nomenclature
  • Famiglietti and Kolb 1975 call this cell the AII
  • Kolb, Nelson and Mariani '81 calls this cell the A7

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