area centralis: 4400 synapses (Freed & Sterling, 1988)
- Bipolar Cell
- @ 9 degrees: 258 bipolar synapses
- @ 1 degree: 434 bipolar synapses
- area centralis - Freed, Smith and Sterling (1992)
Input Synapses Presynaptic Cell Synapse % of BP % of A % of Tot Cone Bipolar cb5/b1 523 85% 12% Cone Bipolar b5 12 2% .3% Rod Bipolar 31 5% .7% Unidentified Bipolar 68 11% 1.5% Bipolar Total 616 100% 14% Amacrine A4? 719 19% 16% Amacrine Total 3784 100% 86% Total 4400 100%
- Amacrine Cell
- area centralis: 86% or 3784 synapses (Freed & Sterling, 1988)
- 19% or 719 synapses of the synapses were frome glycine-accumulating amacrines (suggested A4) (Freed & Sterling, 1988)
- area centralis: 86% or 3784 synapses (Freed & Sterling, 1988)
- 5 - 7 On Alpha Ganglion Cells via electrical synapses Vaney, 1991 cited in Vaney, 1994
- 5 - 7 On Alpha Ganglion Cells via electrical synapses Vaney, 1991 cited in Vaney, 1994
- Lateral Geniculate Nucleus
- Enroth-Cugell and Robson '66
- responds to a grating at any phase (no null point)
- respond to both the onset and offest of a grating
- response is typically a transient burst
- Troy & Robson's '92 gamma distribution function fitted to the Interspike interval histogram of an On Y retinal ganglion cell when it is stimulated by a uniform field.
- The On-center Alpha/Y has a higher mean firing rate than the Off-center Alpha/Y.
- " Steady discharges of X and Y retinal ganglion cells of cat under photopic illuminance" Troy & Robson (1992):
- The interspike interval histograms of the steady-state response to a stationary grating are well described by a gamma distribution function of order 3.5 (stdev 1.7).
- The approx. range of isi's is from 0 to 100 msec.
- Mean firing rate for on-center Y/Alpha:
- 29 spikes/sec (stdev 14) [range]- Troy & Robson
- 33 (16) - Stone and Fukuda
- 46 (13) - Sato et al. (1976)
- Immediate neighboring ISIs are negatively correlated.
- Distal neighbor ISIs are slightly positively correlated.
- Beta/X axonal conductance velocity is slower than Alpha/Y axonal conductance velocity - Cleland, Dubin and Levick, W. R. (1971) & Stone and Hoffmann '71
(Sterling Lab)
- Kier PhD
- 1 degree
- 4506 micrometer2 membrane area,
- 10 synapses/100 micrometer2
- 9 degrees
- 2029 micrometer2 membrane area,
- 13 synapses/100 micrometer2
- Bipolar synaptic density is virtually the same for ON alpha and OFF alpha
- Bipolar synaptic density of Alphas is less than half of that of Betas
- 1 degree
- Freed and Sterling (1988)
area centralis
- 30 um soma
- 180 um span (boycott and Wassle, 1974)
- "Primary dendrites ascended almost vertically through strat 5 and 4 of the inner plexiform layer. Upon reaching stratum 3, these turned horizontally and bifurcated repeatedly."
- "From central to peripheral retina alpha dendritic fields increase about four-fold in diameter (200-800 um), reaching assymptote at about 8mm (Fig. 5A; Figure 7 in Boycott and Wassle, 1974)." Kier, Buchsbaum and Sterling '95
- -> area = (.0314m2 - .503mm2)
- Most synapses were in strata 3 and 4 of the inner plexiform layer and a few were found in strata 5. (Freed & Sterling, 1988)
- b1 contacts the dendrites in strata 3 and 4 of the IPL
- b5 contacts the dendrites at the strata 4 and 5 border of the IPL
- unkown cone bipolars contacts the dendrites in strata 3 and 4 of the IPL
- rb contacts the dendrites mainly in strata 3 of the IPL
- glycinergic amacrine contacts were "mainly in stratum 3, with a few in stratum 4 and none in stratum 5."
- non-glycinergic amacrine contacts were "in strata 3 and 4, with a few in stratum 5"
- GABA - Systemically applied Picrotoxin (known to block GABA) reduces 2nd harmonic component, but has no effect on the fundamental response. (Frishman & Linsenmeier, 1982 as cited by Enroth-Cugell and Freeman, 1987)
- Glycine - there is conflicting evidence in regard to the effects of glycine on On- and Off- Alpha/Y cell responses, but it looks like there is a glycinergic input.
- Glycinergic impact
- 19% (~719 synapses) of the synapses onto the On-Alpha Ganglion cell are from glycine-accumulating amacrine cells (postulated as A4). (Freed and Sterling, 1988)
- Quisqualate and AMPA (which have specialized glutamate receptors) reduced spontaneous and light-evoked activity of the On Alpha/Y cell. "if glycinergic transmission was blocked by strychnine, AMPA excited the cell." Boos, Muller, and Wassle (1990)
- No Glycinergic impact: Strychnine (an antagonist of glycine) does not affect On- and Off- Alpha/Y cell response. (It does reduce the response of the On- and Off- Beta/X cell response.) - Kirby, 1979
- Glycinergic impact
- Increased spiking at spontaneous and stimulated (Boos, Muller and Wassle, 1990)
- glutamate (GLU)
- Asparate (ASP)
- Kainate (KA) - more effective than ASP and GLU at lower concentrations (more effective on X-cells than Y-cells)
- Quisqualate (QQ) and AMPA - looks like (directly or indirectly) QQ excites, but it also appears to excite inhibitory neurons presynaptic to the ganglion cells
- NMDA inhibits (42/46)but they argue that this effect is actually occurring via Gabaergic interneurons: "If the GABAergic transmition was blocked by bicuculline, the NMDA-induced inhibition of ON-Y cells was abolished. We conclude that NMDA activates GABAergic interneurons that in turn reduce the activiity of ON-Y cells."
- The Alpha classification is largely an anatomical distinction for a cat ganglion cell. It is commonly linked with the physiologically classified Y cat ganglion cell (Enroth-Cugell and Robson, 1966; Peichl and Wassle, 1983;Saito, 1983; Fukuda et al, 1984; Stanford and Sherman, 1984)
- X-type and Y-type have also been refered to as brisk (firing) cells or brisk-sustained and brisk-transient. (i.e. Bolz, Wassle and Thier, 1984).
- Class I - i.e. Berson, Pu and Famiglietti '96 ARVO
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