A19 Amacrine

References

• Postsynaptic connections (Input)
  • Freed, Pflug, Kolb and Nelson (1996)

    • Input Synapses

      Presynaptic Cell	Cell #1		Cell #2
      Cone Bipolar total	15	7%	11	19%
      reciprocated	2	1%	5	9%
      unreciprocated	13	6%	6	10%
      Amacrine	207	93%	46	81%
      Total Input	222		57

    • Data on Cell #1 were taken from primary dendrites and some higher order processes in strata 2
    • Data on Cell #2 were taken from primary dendrites near the soma in strata 2 and along the sublamina a/b border
    • Cone Bipolar via ribbon synapse
    • Some of the cone bipolar synapses are reciprocated
    • Amacrine
      • Many Pale Amacrine via conventional synapses - also "In some cases (not shown), we observed a pale amacrine cell profile synapsing on both cell 1 and its postsynaptic OFF-alpha"
      • Few Dark Amacrine via conventional synapses
    • Note: these synapse counts are not totals for the whole cell, but totals for the portion of the cell examined.

• Presynaptic connections (Output)
  • Freed, Pflug, Kolb and Nelson (1996)

    • Output Synapses

      Postsynaptic Cell	Cell #1		Cell #2
      Cone Bipolar total	3	8.3%	5	41.6%
      reciprocated	2	5.6%	5	41.6%
      unreciprocated	1	2.7%	0	0%
      Amacrine	3	8.3%	5	41.6%
      Ganglion Cell	30	83%	2	16.6%
      Total Output	36		12

    • Cone Bipolar via conventional synapse
    • Some of the cone bipolar synapses are reciprocated.
    • Amacrine
    • "virtually all postsynaptic ganglion cell dendrites were from the Off-Alpha" ganglion cell
  

• Function
  • Kolb, Nelson and Mariani (1981)
    • Called an "Off"-lamina morphological counterpart to the A22 (which has dendrites in the "On"-lamina of the IPL.)
  • Freed, Pflug, Kolb and Nelson (1996)
    • On-Off amacrine - "respond with transient depolarizations to both the onset and the offset of a flashing light" - EPSP
    • Two spike-like event sizes
    • Narrow dynamic range: 1 log unit
    • receptive field is larger than dendritic field: a light bar elicited a response from a cell when the bar was "separated from the dendritic arbor by 300 um".
    • No center-surround antagonism
    • fast depolarizations 2 distinct events
      • 1-4 mV
      • Large events = 3-4 mV
      • Small events = 1-2 mV
      • They did not support the idea that small events trigger large events (which has been suggested by others in other cells).

• Morphology
  • Pourcho and Goebel (1983) note: they acknowledge that their cell is small relative to the A19's reported elsewhere
    • unistratified
    • 12 um soma
    • 3 thick dendrites with relatively few branches
    • dendrites have several varicosities and spines
    • ~400 um dendritic field diameter
  • Kolb, Nelson and Mariani (1981)
    • 12-15 um soma which are large and flattened
    • unistratified
    • dendrites have several varicosities and spines

• Array characteristics

• Compartmental Model Characteristics

• Location
  • stratified only in strata 2 of the IPL (Kolb, Nelson and Mariani, 1981; Pourcho and Goebel, 1983)

• Subclasses

• Synapse types

• Synapse Receptors

• Neurotransmitters
  • Accumulates (3H)muscimol inidicative of GABA

• Immunoreactivity

• Nomenclature
  • Originated in Kolb, Nelson and Mariani, 1981

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