Synaptic connectivity in the midget‐parvocellular pathway of primate central retina

Jusuf, Patricia Regina; Martin, Paul R.; Grünert, Ulrike

doi:10.1002/cne.20804

Cited by 67 publications

(91 citation statements)

References 49 publications

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“…It has been suggested that the midget bipolar cells in the central macaque retina show further color selectivity, such that M-cone-contacting midget bipolar cells make different numbers of synapses with midget ganglion cells than L-cone-contacting midget bipolar cells (Calkins et al, 1994). However, we showed recently that the number of synapses made by FMB cells is comparable in dichromat and trichromatic animals (Jusuf et al, 2006), so the differences found by Calkins et al (1994) may not be necessarily related to trichromatic color vision. Here, we found that the mosaic of FMB axon terminals in the peripheral retina is spatially independent of the midget ganglion cell mosaic.…”

Section: Selective Wiring In the Primate Retina?mentioning

confidence: 50%

“…Dye injections were performed as described previously (Szmajda et al, 2005;Jusuf et al, 2006). Briefly, animals were anesthetized with isofluorane (Forthane; Abbott, Sydney, Australia; ICI, 1-2%) and intramuscular ketamine (30 mg/kg) and xylazine hydrochloride (Rompun; Bayer Animal Health Australia, Pymble, New South Wales, Australia; 2-4 g/kg).…”

Section: Retrograde Labeling Of Retinal Ganglion Cells In Marmosetsmentioning

confidence: 99%

“…An estimate of the synaptic input to peripheral midget ganglion cells Central (Ͻ1.25 mm eccentricity) FMB axons in the marmoset retina form ϳ30 synapses onto midget ganglion cells (Jusuf et al, 2006). We calculated the number of contact areas between FMB axons and midget ganglion cell dendrites (putative synaptic sites) for the 252 FMB axons from 2.6 to 5.1 mm eccentricity.…”

Section: Contacts Between Midget Bipolar Axons and Midget Ganglion Cementioning

confidence: 99%

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Random Wiring in the Midget Pathway of Primate Retina

Jusuf¹,

Martin²

2006

J. Neurosci.

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The present study addresses the questions of how topographically organized neuronal populations are connected, and whether there is anatomical evidence for color-selective wiring in retinal pathways for red-green color vision. The connectivity of OFF midget bipolar and OFF midget ganglion cells was studied in the peripheral retina of dichromatic ("red-green color blind") and trichromatic ("color normal") marmosets (Callithrix jacchus). Midget bipolar cells were identified immunohistochemically. Midget ganglion cells were retrogradely labeled from the lateral geniculate nucleus and photofilled. Comparable results were obtained from all retinas studied. Between 3 and 16 bipolar terminals converge onto each ganglion cell. Nearly all bipolar terminals investigated show regions of colocalization (areas of presumed synaptic contacts) with ganglion cell dendrites. This contact area makes up ϳ14% of the axon surface area for a typical midget bipolar cell. The output from individual midget bipolar axons is often shared between midget ganglion cells so that, on average, Ͻ70% of the axon terminal area of a midget bipolar cell shows overlap with the dendritic field of a given midget ganglion cell. We conclude that there is no morphological evidence of red-green color selectivity in the connections between midget bipolar and midget ganglion cell mosaics. Furthermore, the results suggest that convergence is based on local interactions between axons and dendrites rather than cell-by-cell recognition between members of each mosaic.

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Section: Selective Wiring In the Primate Retina?mentioning

confidence: 50%

Section: Retrograde Labeling Of Retinal Ganglion Cells In Marmosetsmentioning

confidence: 99%

Section: Contacts Between Midget Bipolar Axons and Midget Ganglion Cementioning

confidence: 99%

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Random Wiring in the Midget Pathway of Primate Retina

Jusuf¹,

Martin²

2006

J. Neurosci.

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“…Most foveal PC cells derive input from a single L or M cone via a single midget bipolar cell (Kolb and Dekorver, 1991;Calkins et al, 1994;Jusuf et al, 2006a) and thus should get a dominant functional input to the receptive field center from a single cone type. Under the "random wiring" hypothesis (Mollon et al, 1984;Shapley and Perry, 1986;Lennie et al, 1991), this one-to-one connectivity is the dominant source of spectral bias in PC fields and thus produces the afferent signals serving red-green color vision.…”

Section: Introductionmentioning

confidence: 99%

Specificity of M and L Cone Inputs to Receptive Fields in the Parvocellular Pathway: Random Wiring with Functional Bias

Buzás¹,

Blessing²,

Szmajda³

et al. 2006

J. Neurosci.

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Many of the parvocellular pathway (PC) cells in primates show red-green spectral selectivity (cone opponency), but PC ganglion cells in the retina show no anatomical signs of cone selectivity. Here we asked whether responses of PC cells are compatible with "random wiring" of cone inputs. We measured long-wavelength-sensitive (L) and medium-wavelength-sensitive (M) cone inputs to PC receptive fields in the dorsal lateral geniculate of marmosets, using discrete stimuli (apertures and annuli) to achieve functional segregation of center and surround. Receptive fields between the fovea and 30°eccentricity were measured.We show that, in opponent PC cells, the center is dominated by one (L or M) cone type, with normally Ͻ20% contribution from the other cone type (high "cone purity"), whereas non-opponent cells have mixed L and M cone inputs to the receptive field center. Furthermore, opponent response strength depends on the overall segregation of L and M cone inputs to center and surround rather than exclusive input from one cone type to either region. These data are consistent with random wiring. The majority of PC cells in both foveal (Ͻ8°) and peripheral retina nevertheless show opponent responses. This arises because cone purity in the receptive field surround is at least as high as in the center, and the surround in nearly all opponent PC cells is dominated by the opposite cone type to that which dominates the center. These functional biases increase the proportion of opponent PC cells, but their anatomical basis is unclear.

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“…Each midget bipolar cell makes dominant contact with a single midget ganglion cell in the inner plexiform layer. Again in the fovea there is one-to-one connectivity giving a 'private line' for signals from each foveal cone (Jusuf, Martin, & Grünert, 2006a).…”

Section: Cone Pathways In the Foveamentioning

confidence: 99%

Color signals in retina and lateral geniculate nucleus of marmoset monkeys.

Martin¹

2013

Psychology & Neuroscience

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Marmosets show sex-linked polymorphism of color vision, whereby all males and some females show dichromatic ("redgreen color-blind") vision based on two classes of photoreceptor sensitive to short or medium wavelength bands. Most female marmosets by contrast express three photoreceptor classes, one sensitive to short wavelengths and two classes in the mediumlong wavelength sensitivity band. We used this 'natural knock-out' to study the organization of color vision pathways in primates. We review here results from our and other laboratories showing how the primordial dichromatic blue-yellow pathway is characterized by selective connections to short wavelength sensitive cones in the retina and that signals for blue-yellow color vision travel through an ancient part of the subcortical visual pathway called the koniocellular system. Signals serving red-green color vision by contrast are tightly linked to retinal circuits serving high-resolution spatial vision at the fovea and show little sign of specific patterns of connections with medium-and long-wavelength sensitive cones. Routine trichromatic color vision thus is based on converging signals from two quite distinct retinal and subcortical pathways.

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Synaptic connectivity in the midget‐parvocellular pathway of primate central retina

Cited by 67 publications

References 49 publications

Random Wiring in the Midget Pathway of Primate Retina

Random Wiring in the Midget Pathway of Primate Retina

Specificity of M and L Cone Inputs to Receptive Fields in the Parvocellular Pathway: Random Wiring with Functional Bias

Color signals in retina and lateral geniculate nucleus of marmoset monkeys.

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