scholarly journals Synaptic organization of thalamocortical axon collaterals in the perigeniculate nucleus and dorsal lateral geniculate nucleus

2008 ◽  
Vol 508 (2) ◽  
pp. 264-285 ◽  
Author(s):  
Martha E. Bickford ◽  
Haiyang Wei ◽  
Michael A. Eisenback ◽  
Ranida D. Chomsung ◽  
Arkadiusz S. Slusarczyk ◽  
...  
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Synaptic Organization ◽  
Perigeniculate Nucleus ◽  
Lateral Geniculate ◽  
Axon Collaterals ◽  
Dorsal Lateral Geniculate

The histaminergic innervation of the lateral geniculate complex in the cat

1993 ◽  
Vol 10 (2) ◽  
pp. 225-235 ◽  
Author(s):  
Daniel J. Uhlrich ◽  
Karen A. Manning ◽  
Thomas P. Pienkowski
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Optic Chiasm ◽  
Cell System ◽  
Posterior Hypothalamus ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Cell Group ◽  
Perigeniculate Nucleus ◽  
Lateral Geniculate ◽  
Large Round ◽  
Dorsal Lateral Geniculate

AbstractThe histaminergic innervation of the thalamic dorsal and ventral lateral geniculate nuclei and the perigeniculate nucleus of the cat was examined immunohistochemically by means of an antibody to histamine.We find histamine-immunoreactive neurons in the cat brain are concentrated in the ventrolateral portion of the posterior hypothalamus, confirming a previous report. However, this cell group also spreads into medial, dorsal, and extreme lateral regions of the posterior hypothalamus and extends as far rostral as the optic chiasm.Histamine-labeled fibers cover all regions of the lateral geniculate complex, but the density of labeling varies. The ventral lateral geniculate nucleus (vLGN) is most densely labeled, the A laminae of the dorsal lateral geniculate are sparsely labeled, and the geniculate C laminae and the perigeniculate nucleus show intermediate amounts of label. Thus, histaminergic fibers demonstrate a predilection for zones innervated by the W-cell system. Labeled fibers exhibit few branchings and numerousen passantswellings, lending a beaded appearance. The vLGN showed more instances of fibers with larger-sized swellings (up to 2 μm).Following injections of biotinylated tracers into the hypothalamus, we find labeled fibers throughout the lateral geniculate complex. The anterogradely labeled fibers resemblethe histaminergic fibers in morphology, distribution, and relative bouton size. Thus, the hypothalamus appears to be the source of the histaminergic fibers in the lateral geniculate complex.Histamine-labeled fibers in the dorsal lateral geniculate nucleus (dLGN) exhibit uncommon ultrastructural morphology. Many extremely large, round, or elliptical vesicles fill the fiber swellings. Swellings are directly apposed to a variety of other dendritic and axonal profiles, but thus far no convincing synaptic contacts have been seen. The distribution and appearance of these histaminergic fibers resembles those reported for serotonergic fibers.Our results support the idea that histamine works nonsynaptically as a neuromodulator in the lateral geniculate complex, affecting the level of visual arousal.

The β sector of the rabbit's dorsal lateral geniculate nucleus

1988 ◽  
Vol 233 (1270) ◽  
pp. 17-32 ◽  
Keyword(s):  
Visual Cortex ◽  
Lateral Geniculate Nucleus ◽  
Cortical Neurons ◽  
Main Part ◽  
Small Region ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Axon Terminals ◽  
Perigeniculate Nucleus ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

The β sector of the rabbit’s dorsal lateral geniculate nucleus is a small region of nerve cells scattered among the fibres of the geniculocortical pathway. In its topographical relations it resembles the perigeniculate nucleus of carnivores, which contains neurons driven by geniculate and visual cortical neurons and which sends inhibitory fibres back into the geniculate relay. We have traced retinogeniculate, geniculocortical and corticogeniculate pathways in rabbits by using horseradish peroxidase or radioactively labelled proline and have found that the β sector resembles the perigeniculate nucleus in receiving no direct retinal afferents, sending no efferents to the visual cortex (V–I), and receiving afferents from the visual cortex. The corticogeniculate afferents are organized so that the visual field map in the β sector and the main part of the lateral geniculate relays are aligned, as are the maps in the cat’s perigeniculate nucleus and the main part of the geniculate relay of carnivores. Electron microscopical studies show similar types of axon terminals in the rabbit and the cat for the main part of the geniculate relay on the one hand and for the β sector and the perigeniculate nucleus on the other. Earlier observations that the proportion of putative inhibitory terminals (F-type terminals) is lower in the rabbit’s than the cat’s geniculate region are confirmed. A major difference between the β sector and the perigeniculate nucleus has been revealed by immunohistochemical staining for GABA. Whereas almost all of the cat’s perigeniculate cells appear to be GABA ergic, the proportion in the β sector is much lower, and not significantly different from that found in the main part of the rabbit’s geniculate relay. It is concluded that the β sector shares many of the organizational features of the perigeniculate nucleus. A common developmental origin seems probable, but the functional differences remain to be explored.

Synaptic organization of the dorsal lateral geniculate nucleus in the adult hamster

1985 ◽  
Vol 171 (2) ◽  
pp. 223-234 ◽  
Author(s):  
K. -F. So ◽  
G. Campbell ◽  
A. R. Lieberman
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Synaptic Organization ◽  
Lateral Geniculate ◽  
Adult Hamster ◽  
Dorsal Lateral Geniculate

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.

Quantitative immunogold evidence for enrichment of glutamate but not aspartate in synaptic terminals of retino-geniculate, geniculo-cortical, and cortico-geniculate axons in the cat

1994 ◽  
Vol 11 (4) ◽  
pp. 675-681 ◽  
Author(s):  
Vicente M. Montero
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Glial Cells ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Selective Enrichment ◽  
Perigeniculate Nucleus ◽  
Synaptic Terminals ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

AbstractA postembedding immunogold procedure was used on thin sections of the dorsal lateral geniculate nucleus (LGN) and perigeniculate nucleus (PGN) of the cat to estimate qualitatively and quantitatively, at the electron-microscopic (EM) level, the intensity of glutamate or aspartate immunoreactivities on identifiable synaptic terminals and other profiles of the neuropil. On sections incubated with a glutamate antibody, terminals of retinal and cortical axons in the LGN, and of collaterals of geniculo-cortical axons in the PGN, contain significantly higher density of immunogold particles than GABAergic terminals, glial cells, dendrites, and cytoplasm of geniculate cells. By contrast, in sections incubated with an aspartate antibody, terminals of retino-geniculate, cortico-geniculate, and geniculo-cortical axons did not show a selective enrichment of immunoreactivity, but instead the density of immunogold particles was generally low in the different profiles of the neuropil, with the exception of nucleoli. These results suggest that glutamate, but not aspartate, is a neurotransmitter candidate in the retino-geniculo-cortical pathways.

scholarly journals Are the Interlaminar Zones of the Ferret Dorsal Lateral Geniculate Nucleus Actually Part of the Perigeniculate Nucleus?

1996 ◽  
Vol 16 (19) ◽  
pp. 5923-5941 ◽  
Author(s):  
Maria V. Sanchez-Vives ◽  
Thierry Bal ◽  
Uhnoh Kim ◽  
Marcus von Krosigk ◽  
David A. McCormick
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Perigeniculate Nucleus ◽  
Lateral Geniculate ◽  
Dorsal Lateral Geniculate

Organization of reciprocal connections between the perigeniculate nucleus and dorsal lateral geniculate nucleus in the cat: A transneuronal transport study

2002 ◽  
Vol 19 (4) ◽  
pp. 511-520 ◽  
Author(s):  
T. FITZGIBBON
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Ocular Dominance ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Thalamic Reticular Nucleus ◽  
Reticular Nucleus ◽  
Perigeniculate Nucleus ◽  
Lateral Geniculate ◽  
Efferent Projections ◽  
Contralateral Eye ◽  
Dorsal Lateral Geniculate

Cells of the cat's perigeniculate nucleus (PGN), part of the visual sector of the thalamic reticular nucleus (TRN), provide GABAergic inhibition to the A and A1 layers of the dorsal lateral geniculate nucleus (LGNd) and, therefore, may control information flow from the retina to the cortex. Previous electrophysiological experiments suggested that the PGN may be subdivided on the basis of ocular dominance thus reflecting the afferent and efferent projections with lamina A and A1 of the LGNd. The present study utilized the ability of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) to be transported transneuronally following intraocular injections in four cats to examine whether there is any anatomical evidence for eye specific layers within the PGN. Sections were processed with tetramethylbenzidine. Light WGA-HRP transneuronal labeling of LGNd collaterals and somata were seen in the PGN and very light labeling (but not somata) was seen in the TRN. Neither the cells of the PGN projecting to the LGNd nor the LGNd relay collaterals within the PGN were clearly organized into nonoverlapping laminae related to the eye specific layers of the LGNd. However, parts of the PGN immediately adjacent to the LGNd appear devoid of connections with lamina A1 thus creating a thin monocular segment for the contralateral eye.

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