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Dorsal Lateral Geniculate Nucleus (dorsal + lateral_geniculate_nucleus)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

The Developmental Remodeling of Eye-Specific Afferents in the Ferret Dorsal Lateral Geniculate Nucleus

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2010
Colenso M. Speer
Abstract Eye-specific projections to the dorsal lateral geniculate nucleus (dLGN) serve as a model for exploring how precise patterns of circuitry form during development in the mammalian central nervous system. Using a combination of dual-label anterograde retinogeniculate tracing and Nissl-staining, we studied the patterns of eye-specific afferents and cellular laminae in the dLGN of the pigmented sable ferret at eight developmental timepoints between birth and adulthood. Each time point was investigated in the three standard orthogonal planes of section, allowing us to generate a complete anatomical map of eye-specific development in this species. We find that eye-specific retinal ganglion cell axon segregation varies according to location in the dLGN, with the principle contralateral (A) and ipsilateral layers (A1) maturing first, followed by the contralateral and ipsilateral C laminae. Cytoarchitectural lamination lags behind eye-specific segregation, except in the C laminae where underlying cellular layers never develop to accompany eye-specific afferent domains. The emergence of On/Off sublaminae occurs following eye-specific segregation in this species. On the basis of these findings, we constructed a three-dimensional map of eye-specific channels in the developing and mature ferret dLGN. Anat Rec, 293:1,24, 2010. © 2010 Wiley-Liss, Inc. [source]

Serum or target deprivation-induced neuronal death causes oxidative neuronal accumulation of Zn2+ and loss of NAD+

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2010
Christian T. Sheline
Abstract Trophic deprivation-mediated neuronal death is important during development, after acute brain or nerve trauma, and in neurodegeneration. Serum deprivation (SD) approximates trophic deprivation in vitro, and an in vivo model is provided by neuronal death in the mouse dorsal lateral geniculate nucleus (LGNd) after ablation of the visual cortex (VCA). Oxidant-induced intracellular Zn2+ release ([Zn2+]i) from metallothionein-3 (MT-III), mitochondria or ,protein Zn2+', was implicated in trophic deprivation neurotoxicity. We have previously shown that neurotoxicity of extracellular Zn2+ required entry, increased [Zn2+]i, and reduction of NAD+ and ATP levels causing inhibition of glycolysis and cellular metabolism. Exogenous NAD+ and sirtuin inhibition attenuated Zn2+ neurotoxicity. Here we show that: (1) Zn2+ is released intracellularly after oxidant and SD injuries, and that sensitivity to these injuries is proportional to neuronal Zn2+ content; (2) NAD+ loss is involved , restoration of NAD+ using exogenous NAD+, pyruvate or nicotinamide attenuated these injuries, and potentiation of NAD+ loss potentiated injury; (3) neurons from genetically modified mouse strains which reduce intracellular Zn2+ content (MT-III knockout), reduce NAD+ catabolism (PARP-1 knockout) or increase expression of an NAD+ synthetic enzyme (Wlds) each had attenuated SD and oxidant neurotoxicities; (4) sirtuin inhibitors attenuated and sirtuin activators potentiated these neurotoxicities; (5) visual cortex ablation (VCA) induces Zn2+ staining and death only in ipsilateral LGNd neurons, and a 1 mg/kg Zn2+ diet attenuated injury; and finally (6) NAD+ synthesis and levels are involved given that LGNd neuronal death after VCA was dramatically reduced in Wlds animals, and by intraperitoneal pyr vate or nicotinamide. Zn2+ toxicity is involved in serum and trophic deprivation-induced neuronal death. [source]

Depression of retinogeniculate synaptic transmission by presynaptic D2 -like dopamine receptors in rat lateral geniculate nucleus

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2006
G. Govindaiah
Abstract Extraretinal projections onto neurons in the dorsal lateral geniculate nucleus (dLGN) play an important role in modifying sensory information as it is relayed from the visual thalamus to neocortex. The dLGN receives dopaminergic innervation from the ventral tegmental area; however, the role of dopamine in synaptic transmission in dLGN has not been explored. In the present study, whole cell recordings were obtained to examine the actions of dopamine on glutamatergic synaptic transmission. Dopamine (2,100 µm) strongly suppressed excitatory synaptic transmission in dLGN relay neurons that was evoked by optic tract stimulation and mediated by both N -methyl- d -aspartate and non -N -methyl- d -aspartate glutamate receptors. In contrast, dopamine did not alter inhibitory synaptic transmission arising from either dLGN interneurons or thalamic reticular nucleus neurons. The suppressive action of dopamine on excitatory synaptic transmission was mimicked by the D2 -like dopamine receptor agonist bromocriptine (2,25 µm) but not by the D1 -like receptor agonist SKF38393 (10,25 µm). In addition, the dopamine-mediated suppression was antagonized by the D2 -like receptor antagonist sulpiride (10,20 µm) but not by the D1 -like receptor antagonist SCH23390 (5,25 µm). The dopamine-mediated decrease in evoked excitatory postsynaptic current amplitude was accompanied by an increase in the magnitude of paired-pulse depression. Furthermore, dopamine also reduced the frequency but not the amplitude of miniature excitatory postsynaptic currents. Taken together, these data suggest that dopamine may act presynaptically to regulate the release of glutamate at the retinogeniculate synapse and modify transmission of visual information in the dLGN. [source]

Auditory activation of ,visual' cortical areas in the blind mole rat (Spalax ehrenbergi)

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002
Gilles Bronchti
Abstract The mole rat (Spalax ehrenbergi) is a subterranean rodent whose adaptations to its fossorial life include an extremely reduced peripheral visual system and an auditory system suited for the perception of vibratory stimuli. We have previously shown that in this blind rodent the dorsal lateral geniculate nucleus, the primary visual thalamic nucleus of sighted mammals, is activated by auditory stimuli. In this report we focus on the manifestation of this cross-modal compensation at the cortical level. Cyto- and myeloarchitectural analyses of the occipital area showed that despite the almost total blindness of the mole rat this area has retained the organization of a typical mammalian primary visual cortex. Application of the metabolic marker 2-deoxyglucose and electrophysiological recording of evoked field potentials and single-unit activity disclosed that a considerable part of this area is activated by auditory stimuli. Previous neuronal tracing studies had revealed the origin of the bulk of this auditory input to be the dorsal lateral geniculate nucleus which itself receives auditory input from the inferior colliculus. [source]

Neurogenic development of the visual areas in the Chinese softshell turtle (Pelodiscus sinensis) and evolutionary implications

JOURNAL OF ANATOMY, Issue 5 2008
Chao Xi
Abstract To characterize the neurogenic development of the visual areas of the turtle (Pelodiscus sinensis) during embryogenesis, a single dose of [3H]-thymidine (10 µCi) was injected into egg yolks from stages S11~12 to S21. At hatching, localization of [3H]-thymidine incorporation was examined, and led to three main observations. (1) Neurogenesis occurred in the stratum griseum centrale of the tectum opticum from S11~12 to S16 with a peak at S12. No obvious gradients of neurogenesis were observed. (2) Neurogenesis in the nucleus rotundus (Rot) and in the dorsal lateral geniculate nucleus (GLd) occurred from S11~12 to S15. Gradients of neurogenesis were detected along ventral,dorsal and lateral,medial axes in the Rot, but only the latter neurogenic gradient occurred in the GLd. (3) In the visual region of the dorsal ventricular ridge, neurogenesis lasted from S11~12 to S16. Similarly, neurogenesis occurred from S11~12 to S16~17 in the dorsal cortex, with a peak at S12 for both telencephalic visual regions. Neurogenesis followed a ventrolateral to dorsomedial gradient in the visual region of the dorsal ventricular ridge, and a superficial to deep gradient in the caudal dorsal cortex. A significant number of neurons in the rostral dorsal cortex followed a deep (earlier arising) to superficial (later arising) pattern of neurogenesis, similar to that in the avian Wulst or in the mammalian isocortex. Finally, we compared the timing and development of neurogenesis in the turtle with birds and mammals to understand the evolutionary implications of these processes. [source]