scholarly journals Not a one-trick pony: Diverse connectivity and functions of the rodent lateral geniculate complex

2017 ◽  
Vol 34 ◽  
Author(s):  
ABOOZAR MONAVARFESHANI ◽  
UBADAH SABBAGH ◽  
MICHAEL A. FOX
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Ganglion Cells ◽  
Sensory Information ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Projection Neurons ◽  
Retinal Ganglion ◽  
Unique Role ◽  
Visual Thalamus ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

AbstractOften mislabeled as a simple relay of sensory information, the thalamus is a complicated structure with diverse functions. This diversity is exemplified by roles visual thalamus plays in processing and transmitting light-derived stimuli. Such light-derived signals are transmitted to the thalamus by retinal ganglion cells (RGCs), the sole projection neurons of the retina. Axons from RGCs innervate more than ten distinct nuclei within thalamus, including those of the lateral geniculate complex. Nuclei within the lateral geniculate complex of nocturnal rodents, which include the dorsal lateral geniculate nucleus (dLGN), ventral lateral geniculate nucleus (vLGN), and intergeniculate leaflet (IGL), are each densely innervated by retinal projections, yet, exhibit distinct cytoarchitecture and connectivity. These features suggest that each nucleus within this complex plays a unique role in processing and transmitting light-derived signals. Here, we review the diverse cytoarchitecture and connectivity of these nuclei in nocturnal rodents, in an effort to highlight roles for dLGN in vision and for vLGN and IGL in visuomotor, vestibular, ocular, and circadian function.

Transneuronal degeneration of beta retinal ganglion cells in the cat

1984 ◽  
Vol 222 (1226) ◽  
pp. 15-32 ◽  
Keyword(s):  
Visual Cortex ◽  
Retinal Ganglion Cells ◽  
Lateral Geniculate Nucleus ◽  
Ganglion Cells ◽  
Dendritic Morphology ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Retinal Ganglion ◽  
Normal Numbers ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

Transneuronal retrograde degeneration of retinal ganglion cells was investigated following neonatal visual cortex ablation in the cat. After a survival time of at least 18 months, retinal ganglion cells projecting to the thalamus were labelled by retrograde transport of horseradish peroxidase. Filled ganglion cells were classified into α , β and γ types on the basis of dendritic morphology. In normal cats, α cells made up 8-10% of the total population in the sample area, β cells made up 64-67% and γ cells made up 23-27%. In retinae of visual cortex-ablated cats, normal numbers of α and γ cells were present, but the β cell population was depleted by 90% of normal. Thalamic projections of surviving retinal ganglion cells were investigated by anterograde transport of tritiated proline injected into the eye. In these animals, ablation of visual cortex resulted in almost complete degeneration of laminae A and A1 of the dorsal lateral geniculate nucleus. In the radioautographic material, projections from the retina to the degenerated parts of laminae A and A1 were barely detectable. Survival of some ganglion cell populations and death of others after neonatal visual cortex ablation may be explained in terms of the pattern of projections of the different cell types. We conclude that the majority of β cells degenerate following visual cortex ablation because of removal of cells in the dorsal lateral geniculate nucleus which form their sole or principal target. Alpha and γ cells and 10% of β -cells survive because of extensive collateral projections to targets other than cells of the laminae A and A1 of dorsal lateral geniculate nucleus.

Mathematical models for the spatial receptive-field organization of nonlagged X-cells in dorsal lateral geniculate nucleus of cat

2000 ◽  
Vol 17 (6) ◽  
pp. 871-885 ◽  
Author(s):  
G.T. EINEVOLL ◽  
P. HEGGELUND
Keyword(s):  
Receptive Field ◽  
Ganglion Cell ◽  
Lateral Geniculate Nucleus ◽  
Discrete Model ◽  
Receptive Fields ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Retinal Ganglion ◽  
Lateral Geniculate ◽  
X Cells ◽  
Dorsal Lateral Geniculate

Spatial receptive fields of relay cells in dorsal lateral geniculate nucleus (dLGN) have commonly been modeled as a difference of two Gaussian functions. We present alternative models for dLGN cells which take known physiological couplings between retina and dLGN and within dLGN into account. The models include excitatory input from a single retinal ganglion cell and feedforward inhibition via intrageniculate interneurons. Mathematical formulas describing the receptive field and response to circular spot stimuli are found both for models with a finite and an infinite number of ganglion-cell inputs to dLGN neurons. The advantage of these models compared to the common difference-of-Gaussians model is that they, in addition to providing mathematical descriptions of the receptive fields of dLGN neurons, also make explicit contributions from the geniculate circuit. Moreover, the model parameters have direct physiological relevance and can be manipulated and measured experimentally. The discrete model is applied to recently published data (Ruksenas et al., 2000) on response versus spot-diameter curves for dLGN cells and for the retinal input to the cell (S-potentials). The models are found to account well for the results for the X-cells in these experiments. Moreover, predictions from the discrete model regarding receptive-field sizes of interneurons, the amount of center-surround antagonism for interneurons compared to relay cells, and distance between neighboring retinal ganglion cells providing input to interneurons, are all compatible with data available in the literature.

Effects of eliminating retinal Y cell input on center-surround interactions in the dorsal lateral geniculate nucleus of the cat

1996 ◽  
Vol 13 (6) ◽  
pp. 1089-1097 ◽  
Author(s):  
Chun Wang ◽  
B. Dreher ◽  
W. Burke
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Ganglion Cells ◽  
Spot Size ◽  
Excitatory Input ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Optimal Size ◽  
Lateral Geniculate ◽  
Optic Fibers ◽  
Dorsal Lateral Geniculate ◽  
Suppression Index

AbstractThe aim of this project was to investigate the interaction between Y retinal ganglion cells and the cells of the dorsal lateral geniculate nucleus (LGNd) of the cat, with particular reference to center-surround antagonism and intrageniculate inhibition. Responses of cells in the LGNd were studied by stimulating the retina with spots of light of constant contrast but varying size. The peak discharges of nonlagged X (XN) cells were strongly suppressed with increase in spot size but the responses of lagged X (XL) cells and nonlagged Y (YN) cells were inhibited much less strongly. The effect of the Y system on these responses was examined by producing a selective block of conduction in Y fibers in one optic nerve by means of a pressure cuff (Y-blocking). These effects were assessed by measuring the peak discharge rates and by calculation of a “peak suppression index.” Y-blocking had no significant effect on the peak suppression index of XL, cells in either lamina or on YN cells in the normal (not Y-blocked) lamina but had significant effects on the responses of XN cells, causing a decrease in peak suppression index, both for cells in laminae receiving their principal excitatory input from the Y-blocked eye (both lamina A and lamina A1 ) as well as those in lamina A (but not lamina A1 ) receiving their excitatory input from the normal eye. These effects were obtained with relatively large spots of light. Thus Y optic fibers have both intralaminar (monocular) and interlaminar (binocular) inhibitory effects on XN cells. In addition to these suppressive effects, the experiments also show that ipsilaterally projecting Y fibers have facilitatory effects on XN cells in lamina A when small spots of light, about optimal size for the XN cell, are used. These results suggest that the Y system plays a powerful role in shaping the responses of XN cells, possibly enhancing visual acuity.

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.

Quantitative analyses of synaptic contacts of interneurons in the dorsal lateral geniculate nucleus of the squirrel monkey

1996 ◽  
Vol 13 (6) ◽  
pp. 1129-1142 ◽  
Author(s):  
James R. Wilson ◽  
Donna M. Forestner ◽  
Ryan P. Cramer
Keyword(s):  
Squirrel Monkey ◽  
Lateral Geniculate Nucleus ◽  
Receptive Fields ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Saimiri Sciureus ◽  
Projection Neurons ◽  
Parvocellular Pathway ◽  
Synaptic Contacts ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

AbstractThree interneurons were recorded from and then injected with horseradish peroxidase in the parvocellular laminae of the squirrel monkey's (Saimiri sciureus) dorsal lateral geniculate nucleus. They were then examined using the electron microscope for their synaptic contacts, both the afferent contacts onto their dendrites and their presynaptic dendritic contacts onto presumptive projection (relay) neuron dendrites. The somata of these interneurons were small (mean = 178 μm2), but the dendritic trees were large compared with those of projection neurons. All three interneurons had similar synaptic patterns onto their dendrites with about equal numbers of retinal, cortical, and GABAergic contacts. The distribution of these contacts was more uniform compared with the same types of contacts made onto projection neurons. The presynaptic dendrites were observed to contact only the dendrites of presumptive projection neurons, and these contacts were nearly all in the form of geniculate triads. None of the three interneurons displayed an axon. The receptive fields of these interneurons were similar to those of projection cells, but were larger and had center-response signs that were the opposite of the projection neurons around them (e.g. OFF center for the dorsal part of the parvocellular mass where ON-center projection neurons reside). The squirrel monkey data provides additional evidence that one aspect of the laminar pattern observed in the parvocellular pathway of the primate's dLGN might be related to a segregation of projection neurons of one center-response sign with interneurons of the opposite center-response sign.

Morphological diversity in terminals of W-type retinal ganglion cells at projection sites in cat brain

1996 ◽  
Vol 13 (3) ◽  
pp. 449-460 ◽  
Author(s):  
Boqing Chen ◽  
Xiao-Jiang Hu ◽  
Roberta G. Pourcho
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Synaptic Vesicles ◽  
Ganglion Cells ◽  
Morphological Diversity ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Anterograde Transport ◽  
Lateral Geniculate ◽  
Morphological Criteria ◽  
Cat Brain ◽  
Dorsal Lateral Geniculate

AbstractThe morphological features of retinal terminals in cat brain were examined at sites where projections of W-type ganglion cells predominate. These included the parvicellular C laminae of the dorsal lateral geniculate nucleus, the ventral lateral geniculate nucleus, stratum griseum superficiale of the superior colliculus, and the suprachiasmatic nucleus. Positive identification of retinal terminals was achieved following anterograde transport of intravitreally injected native or wheat germ agglutinin-conjugated horseradish peroxidase. In contrast to the classic features of retinal terminals as defined from sites where X- and Y-type ganglion cells predominate, i.e. round synaptic vesicles, large profiles, and pale mitochondria, substantial numbers of terminals in W-cell rich areas were found to contain dark mitochondria. Synaptic vesicles, although consistently round, were typically smaller in terminals with dark mitochondria than in those with pale mitochondria. These findings indicate a diversity among terminals of W-cells and suggest that such terminals cannot be distinguished on the basis of limited morphological criteria.

How much feedback from visual cortex to lateral geniculate nucleus in cat: A perspective

2004 ◽  
Vol 21 (4) ◽  
pp. 487-500 ◽  
Author(s):  
JULIAN M.L. BUDD
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Sensory Information ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Synaptic Organization ◽  
Lateral Geniculate ◽  
Order Of Magnitude ◽  
Efferent Neurons ◽  
Cortical Synapses ◽  
Corticothalamic Feedback ◽  
Dorsal Lateral Geniculate

Corticothalamic feedback is believed to play an important role in selectively regulating the flow of sensory information from thalamus to cortex. But despite its importance, the size and nature of corticothalamic pathway connectivity is not fully understood. In light of recent empirical data, the aim of this paper was to quantify the contribution of area 17 axon connectivity to the synaptic organization of A-laminae in dorsal lateral geniculate nucleus (dLGN) in cat, the best studied corticothalamic pathway. Numerical constraints indicate that most corticogeniculate synapses are not formed with inhibitory interneurons. However, the main finding is that there was an order of magnitude difference between estimates of the mean number of cortical synapses per A-laminae neuron based on individual corticogeniculate axon data (12,000–16,000 cortical synapses per cell) than that previously derived from partial reconstructions of the synaptic input to two physiologically identified relay cells (1200–1500 cortical synapses per cell). In an attempt to reconcile these different estimates, parameter variation and comparative analyses suggest that previous work may have overestimated the density of corticogeniculate efferent neurons and underestimated the total number of synapses per geniculate neuron. But as this analysis did not include area 18 corticogeniculate axons innervating A-laminae, the discrepancy between different estimates may be greater and require further explanation. Thus, the analysis presented here suggests geniculate neurons receive on average a greater number of cortical synapses per cell but from far fewer corticogeniculate axons than previously thought.

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