Laminar organization of tree shrew dorsal lateral geniculate nucleus

1983 ◽  
Vol 50 (6) ◽  
pp. 1330-1342 ◽  
Author(s):  
J. L. Conway ◽  
P. H. Schiller
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Tree Shrew ◽  
Visual Stimuli ◽  
Optic Tract ◽  
Cell Types ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Lateral Geniculate ◽  
Tupaia Glis ◽  
Dorsal Lateral Geniculate ◽  
Laminar Specificity

This study investigated the organization of the dorsal lateral geniculate nucleus (LGN) of the tree shrew (Tupaia glis) using both microelectrode recording and anatomical techniques. The tree shrew LGN contains approximately 100,000 cells, of which 20% are in layers 2 and 6. These two layers receive input from the ipsilateral eye. The topography of the tree shrew LGN was delineated by taking systematic penetrations through the structure. Examination of the organization of the LGN laminae showed the following: in layer 1 (the lamina next to the optic tract) a mixture of on-center, off-center and on-off center cells was found; the majority of these cells responded transiently to visual stimuli and they had slightly longer conduction latencies than did cells in the other laminae. On-center and off-center cells in laminae 2-6 were sharply segregated: layers 2, 3, and 4 contained off-center cells and layers 5 and 6 contained on-center cells. Most of the cells in laminae 2-6 responded in a sustained manner to visual stimuli. These results suggest that one function of the LGN lamina is to group cells into various classes. Such grouping has now been shown to occur partially or completely for 1) eye of origin, 2) cell types characterized as on-center and off-center, and 3) cell types characterized as producing transient and sustained responses. The nature and degree of laminar specificity, however, varies considerably from species to species.

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.

scholarly journals Melanopsin-driven increases in maintained activity enhance thalamic visual response reliability across a simulated dawn

2015 ◽  
Vol 112 (42) ◽  
pp. E5734-E5743 ◽  
Author(s):  
Riccardo Storchi ◽  
Nina Milosavljevic ◽  
Cyril G. Eleftheriou ◽  
Franck P. Martial ◽  
Patrycja Orlowska-Feuer ◽  
...  
Keyword(s):  
Light Intensity ◽  
Lateral Geniculate Nucleus ◽  
Visual Stimuli ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Visual Response ◽  
Visual Responses ◽  
Silent Substitution ◽  
Background Light ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

Twice a day, at dawn and dusk, we experience gradual but very high amplitude changes in background light intensity (irradiance). Although we perceive the associated change in environmental brightness, the representation of such very slow alterations in irradiance by the early visual system has been little studied. Here, we addressed this deficit by recording electrophysiological activity in the mouse dorsal lateral geniculate nucleus under exposure to a simulated dawn. As irradiance increased we found a widespread enhancement in baseline firing that extended to units with ON as well as OFF responses to fast luminance increments. This change in baseline firing was equally apparent when the slow irradiance ramp appeared alone or when a variety of higher-frequency artificial or natural visual stimuli were superimposed upon it. Using a combination of conventional knockout, chemogenetic, and receptor-silent substitution manipulations, we continued to show that, over higher irradiances, this increase in firing originates with inner-retinal melanopsin photoreception. At the single-unit level, irradiance-dependent increases in baseline firing were strongly correlated with improvements in the amplitude of responses to higher-frequency visual stimuli. This in turn results in an up to threefold increase in single-trial reliability of fast visual responses. In this way, our data indicate that melanopsin drives a generalized increase in dorsal lateral geniculate nucleus excitability as dawn progresses that both conveys information about changing background light intensity and increases the signal:noise for fast visual responses.

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