The morphology of collicular and retinal axons ending on small relay (W-like) cells of the primate lateral geniculate nucleus

1993 ◽  
Vol 10 (3) ◽  
pp. 403-418 ◽  
Author(s):  
E. A. Lachica ◽  
V. A. Casagrande
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Striate Cortex ◽  
Optic Tract ◽  
Small Cells ◽  
Retinal Projection ◽  
Axon Terminals ◽  
Retinal Axons ◽  
Bush Baby ◽  
Lateral Geniculate ◽  
Cell Class

AbstractThe lateral geniculate nucleus (LGN) of every primate examined contains a set of small relay cells in addition to separate sets of magnocellular and parvocellular relay cells. These small cells receive a direct retinal projection, and an indirect retinal projection via the superior colliculus (SC). Receptive-field analyses of the small LGN cells in the bush baby, a lorisiform primate, indicate that this cell class is composed of subclasses, similar in physiology to cat W cells. In an effort to identify some of these subclasses, we have examined the morphological features of retinal and collicular axonal arbors that end on small W-like cells in the LGN of the bush baby, Galago crassicaudatus. Small cells in this species are found in a prominent pair of koniocellular (K) layers as well as the interlaminar zones (ILZs).Retinal arbors were examined by bulk iontophoretic injection of horseradish peroxidase into the optic tract. Collicular arbors were filled via iontophoretic injection of biocytin into the superficial layers of the SC. Forty-eight axon arbors were completely reconstructed and quantitatively evaluated. Our findings show that retinal and collicular axon terminals differ in morphology on the basis of a number of criteria. Our analyses also suggest that retinal axons may have a stronger influence on K cells and collicular axons have a stronger influence on ILZ cells. The ramifications of these findings are provocative since these small LGN cells are known to project directly to the cytochrome-oxidase (CO) blobs within striate cortex. This relationship suggests that CO blob cells receive complex visual input not only from magnocellular and parvocellular LGN cells, but also from small cell pathways that are differentially influenced by retinal and collicular cells.

NADPH-diaphorase reactivity in the ventral and dorsal lateral geniculate nuclei of rats

1992 ◽  
Vol 9 (2) ◽  
pp. 211-216 ◽  
Author(s):  
John Mitrofanis
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Total Population ◽  
Ganglion Cells ◽  
Nadph Diaphorase ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Small Cells ◽  
Double Labeling ◽  
Lateral Geniculate ◽  
Cell Class ◽  
Dorsal Lateral Geniculate

AbstractThe present study describes the patterns of NADPH-diaphorase reactivity in the ventral and dorsal lateral geniculate nuclei of rats. In the ventral lateral geniculate nucleus, two distinct populations of NADPH-diaphorase reactive cells are apparent. One population is deeply stained, generally larger in somal size and located in the more superficial or dorsolateral regions of the nucleus. The second population of reactive cells in the nucleus is lightly labeled, small in somal size, and found in deeper or more ventromedial regions of the nucleus. Double labeling with an antibody to GAB A revealed that neither cell class is GABAergic.In the dorsal lateral geniculate nucleus, reactivity is apparent in lightly labeled small cells only, most of which are GABA immunoreactive also. The NADPH-diaphorase reactive cells, however, form only a small proportion of the total population of GABAergic cells in the nucleus. The striking feature of the NADPH-diaphorase reactive cells in the dorsal lateral geniculate nucleus is their spatial distribution. Most cells are located in the more superficial or dorsolateral areas: very few are apparent in deeper or more ventromedial areas of the nucleus. This distribution closely parallels the location of the outer “shell” region of the nucleus (see Reese, 1988), which receives most of its afferents from the smaller class II and III ganglion cells of the retina and from the superior colliculus.

Organization of Binocular Pathways: Modeling and Data Related to Rivalry

1991 ◽  
Vol 3 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Sidney R. Lehky ◽  
Randolph Blake
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Binocular Rivalry ◽  
Striate Cortex ◽  
Reciprocal Inhibition ◽  
Lateral Geniculate ◽  
Layer 4 ◽  
Inhibitory Coupling ◽  
Binocular Matching

It is proposed that inputs to binocular cells are gated by reciprocal inhibition between neurons located either in the lateral geniculate nucleus or in layer 4 of striate cortex. The strength of inhibitory coupling in the gating circuitry is modulated by layer 6 neurons, which are the outputs of binocular matching circuitry. If binocular inputs are matched, the inhibition is modulated to be weak, leading to fused vision, whereas if the binocular inputs are unmatched, inhibition is modulated to be strong, leading to rivalrous oscillations. These proposals are buttressed by psychophysical experiments measuring the strength of adaptational aftereffects following exposure to an adapting stimulus visible only intermittently during binocular rivalry.

Retinal Projections in the Northern Native Cat, Dasyurus-Hallucatus (Marsupialia, Dasyuridae)

1987 ◽  
Vol 35 (2) ◽  
pp. 115 ◽  
Author(s):  
AM Harman ◽  
DP Crewther ◽  
JE Nelson ◽  
SG Crewther
Keyword(s):  
Superior Colliculus ◽  
Lateral Geniculate Nucleus ◽  
Optic Tract ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Accessory Optic System ◽  
Anterograde Transport ◽  
Retinal Projections ◽  
Lateral Geniculate ◽  
Contralateral Eye ◽  
Dorsal Lateral Geniculate

The retinal projections of the northern native cat, Dasyurus hallucatus, were studied by the anterograde transport of tritiated proline and by autoradiography. Seven regions in the brain were found to receive direct retinal projections: (1) the suprachiasmatic nucleus; (2) the dorsal lateral geniculate nucleus; (3) the ventral lateral geniculate nucleus; (4) the lateral posterior nucleus; (5) the nuclei of the accessory optic tract; (6) the pretectal nuclei; (7) the superior colliculus. All nuclei studied received a bilateral retinal projection except the medial terminal nucleus of the accessory optic system, in which only a contralateral input was found. The contralateral eye had a greater input in all cases. As with the related species, Dasyurus viverrinus, there is extensive binocular overlap in the dorsal lateral geniculate nucleus (LGNd). In the LGNd contralateral to the injected eye, the autoradiographs show four contralateral terminal bands occupying most of the nucleus. The axonal terminations in the ipsilateral LGNd are more diffuse but show a faint lamination pattern of four bands. The ventral portion of the LGNd receives only contralateral retinal input, and therefore probably represents the monocular visual field. The other principal termination of the optic nerve, the superior colliculus, has a predominantly contralateral input to both sublayers of the stratum griseum superficiale. However, the ipsilateral fibres terminate only in patches in the more inferior sublayer.

Monocular enucleation reduces immunoreactivity to the calcium-binding protein calbindin 28 kD in the Rhesus monkey lateral geniculate nucleus

1992 ◽  
Vol 9 (5) ◽  
pp. 471-482 ◽  
Author(s):  
R. Ranney Mize ◽  
Qian Luo ◽  
Margarete Tigges
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Optical Density ◽  
Calcium Binding ◽  
Striate Cortex ◽  
Binding Protein ◽  
Visual Deprivation ◽  
Calcium Binding Protein ◽  
Monocular Enucleation ◽  
Lateral Geniculate ◽  
Antibody Labeling

AbstractThe calcium-binding proteins calbindin (CaBP) and parvalbumin (PV) are important in regulating intracellular calcium in brain cells. PV immunoreactivity is reduced by enucleation in the lateral geniculate nucleus (LGN) and by enucleation and visual deprivation in the striate cortex of adult monkeys. The effects of enucleation and visual deprivation on CaBP immunoreactivity in the LGN are not known. We therefore have studied cells and neuropil in the LGN that are labeled by antibodies to CaBP in normal and visually deprived Rhesus monkeys to determine if there is an effect on this calcium-binding protein. One group of monkeys had one eye removed 2 weeks to 4.3 years before sacrifice. A second group had one eye occluded with opaque lenses from infancy without enucleation. A final group had one eye occluded long-term followed by short-term enucleation 2 weeks before sacrifice.In normal monkeys, CaBP-immunoreactive neurons were found throughout the LGN. They were sparsely distributed within the six main laminae, and more densely distributed within layer S and the interlaminar zones (ILZ). The labeled ILZ neurons had a distinct morphology, with fusiform somata and elaborate dendritic trees that were confined primarily to the ILZ. Most CaBP-labeled neurons in the main layers had dendrites that radiated in all directions from the soma. ILZ and main layer cells labeled by CaBP thus probably represent two different cell types.Monocular enucleation with or without occlusion produced a significant reduction in antibody labeling in the deafferented laminae. Field measures revealed an average 11.5% reduction in optical density in each deafferented lamina compared to its adjacent, nondeprived layer. The differences in field optical density between deprived and nondeprived layers were statistically significant. CaBP neurons were still visible, but the optical density of antibody labeling in these cells also was reduced. Occlusion without enucleation had no effect. Thus, deafferentation, but not light deprivation, reduces concentrations of CaBP in monkey LGN. This effect is different than that seen in striate cortex of adult monkeys, where visual deprivation as well as enucleation alters CaBP immunoreactivity.

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