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Lateral geniculate nucleus

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https://www.readbyqxmd.com/read/29153326/altered-structural-connectivity-of-the-left-visual-thalamus-in-developmental-dyslexia
#1
Christa Müller-Axt, Alfred Anwander, Katharina von Kriegstein
Developmental dyslexia is a highly prevalent reading disorder affecting about 5%-10% of children [1]. It is characterized by slow and/or inaccurate word recognition skills as well as by poor spelling and decoding abilities [2]. Partly due to technical challenges with investigating subcortical sensory structures, current research on dyslexia in humans by and large focuses on the cerebral cortex [3-7]. These studies found that dyslexia is typically associated with functional and structural alterations of a distributed left-hemispheric cerebral cortex network (e...
November 10, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/29146465/more-than-blindsight-case-report-of-a-child-with-extraordinary-visual-capacity-following-perinatal-bilateral-occipital-lobe-injury
#2
Inaki-Carril Mundinano, Juan Chen, Mitchell de Souza, Marc G Sarossy, Marc F Joanisse, Melvyn A Goodale, James A Bourne
Injury to the primary visual cortex (V1, striate cortex) and the geniculostriate pathway in adults results in cortical blindness, abolishing conscious visual perception. Early studies by Larry Weiskrantz and colleagues demonstrated that some patients with an occipital-lobe injury exhibited a degree of unconscious vision and visually-guided behaviour within the blind field. A more recent focus has been the observed phenomenon whereby early-life injury to V1 often results in the preservation of visual perception in both monkeys and humans...
November 13, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29141247/connections-of-anterior-thalamic-visual-centers-in-the-leopard-frog-rana-pipiens
#3
Eric W Recktenwald, Elizabeth A Dudkin, Laura K Skorina, William M Saidel, Edward R Gruberg
The amphibian retina projects to two discrete regions of neuropil in the anterior thalamus: the neuropil of Bellonci and the corpus geniculatum. These retinorecipient areas are encompassed within a larger zone of surrounding neuropil we call the NCZ (for neuropil of Bellonci/corpus geniculatum zone). The NCZ is characterized electrophysiologically by a distinctive tonic oscillatory response to blue light; it appears to be a visual module involved in processing the stationary visual environment. Using horseradish peroxidase (HRP), we mapped the connections of the NCZ...
November 16, 2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/29129732/chromatic-summation-and-receptive-field-properties-of-blue-on-and-blue-off-cells-in-marmoset-lateral-geniculate-nucleus
#4
C D Eiber, A N J Pietersen, N Zeater, S G Solomon, P R Martin
The "blue-on" and "blue-off" receptive fields in retina and dorsal lateral geniculate nucleus (LGN) of diurnal primates combine signals from short-wavelength sensitive (S) cone photoreceptors with signals from medium/long wavelength sensitive (ML) photoreceptors. Three questions about this combination remain unresolved. Firstly, is the combination of S and ML signals in these cells linear or non-linear? Secondly, how does the timing of S and ML inputs to these cells influence their responses? Thirdly, is there spatial antagonism within S and ML subunits of the receptive field of these cells? We measured contrast sensitivity and spatial frequency tuning for four types of drifting sine gratings: S cone isolating, ML cone isolating, achromatic (S + ML), and counterphase chromatic (S - ML), in extracellular recordings from LGN of marmoset monkeys...
November 9, 2017: Vision Research
https://www.readbyqxmd.com/read/29113752/region-specific-glial-hyperplasia-and-neuronal-stability-of-rat-lateral-geniculate-nucleus-during-aging
#5
Felipe P Fiuza, Antônio Carlos Q Aquino, Diego A Câmara, José Rodolfo L P Cavalcanti, Expedito S Nascimento Júnior, Ramon H Lima, Rovena Clara G J Engelberth, Jeferson S Cavalcante
The normal aging process is accompanied by functional declines in image-forming and non-image forming visual systems. Among the components of these systems, the thalamic lateral geniculate nucleus (LGN) offers a good model for aging studies since its three anatomical subdivisions, namely dorsal lateral geniculate nucleus (dLGN), intergeniculate leaflet (IGL) and ventral lateral geniculate nucleus (vLGN), receives light information from retina and projects to different brain areas involved in visual-related functions...
November 4, 2017: Experimental Gerontology
https://www.readbyqxmd.com/read/29094198/the-turtle-visual-system-mediates-a-complex-spatiotemporal-transformation-of-visual-stimuli-into-cortical-activity
#6
Mahmood S Hoseini, Jeff Pobst, Nathaniel C Wright, Wesley Clawson, Woodrow Shew, Ralf Wessel
The three-layered visual cortex of turtle is characterized by extensive intracortical axonal projections and receives non-retinotopic axonal projections from lateral geniculate nucleus. What spatiotemporal transformation of visual stimuli into cortical activity arises from such tangle of malleable cortical inputs and intracortical connections? To address this question, we obtained band-pass filtered extracellular recordings of neural activity in turtle dorsal cortex during visual stimulation of the retina. We discovered important spatial and temporal features of stimulus-modulated cortical local field potential (LFP) recordings...
November 1, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/29066558/orientation-tuning-of-correlated-activity-in-the-developing-lateral-geniculate-nucleus
#7
Caitlin W Kiley, W Martin Usrey
Neural circuits and the cells that comprise them undergo developmental changes in the spatial organization of their connections and in their temporal response properties. Within the lateral geniculate nucleus (LGN) of the dorsal thalamus, these changes have pronounced effects on the spatiotemporal receptive fields (STRFs) of neurons. An open and unresolved question is how STRF maturation affects stimulus-evoked correlated activity between pairs of LGN neurons during development. This is an important question to answer as stimulus-evoked correlated activity likely plays a role in establishing the specificity of thalamocortical connectivity and the receptive fields of postsynaptic cortical neurons...
October 24, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29059309/elevated-intraocular-pressure-induces-amyloid-%C3%AE-deposition-and-tauopathy-in-the-lateral-geniculate-nucleus-in-a-monkey-model-of-glaucoma
#8
Zhichao Yan, Huanquan Liao, Hongrui Chen, Shuifeng Deng, Yu Jia, Caibin Deng, Jianxian Lin, Jian Ge, Yehong Zhuo
Purpose: Recent evidence has suggested a potential association between Alzheimer's disease (AD) and glaucoma and found significant deposition of amyloid-β (Aβ) and Tau protein in the retinas of glaucoma patients. However, no coherent finding has emerged regarding the AD-like changes in the central visual system (CVS). Studies confirming the presence of Aβ and Tau neuropathology are warranted to identify the underlying mechanism that contributes to the visual impairment observed in glaucoma...
October 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29050909/bold-fmri-in-the-mouse-auditory-pathway
#9
Guilherme Blazquez Freches, Cristina Chavarrias, Noam Shemesh
The auditory pathway is widely distributed throughout the brain, and is perhaps one of the most interesting networks in the context of neuroplasticity. Accurate mapping of neural activity in the entire pathway, preferably noninvasively, and with high resolution, could be instrumental for understanding such longitudinal processes. Functional magnetic resonance imaging (fMRI) has clear advantages for such characterizations, as it is noninvasive, provides relatively high spatial resolution and lends itself for repetitive studies, albeit relying on an indirect neurovascular coupling to deliver its information...
October 16, 2017: NeuroImage
https://www.readbyqxmd.com/read/29023717/recovery-from-the-anatomical-effects-of-long-term-monocular-deprivation-in-cat-lateral-geniculate-nucleus
#10
Kevin R Duffy, Ming-Fai Fong, Donald E Mitchell, Mark F Bear
Monocular deprivation (MD) imposed early in postnatal life elicits profound structural and functional abnormalities throughout the primary visual pathway. The ability of MD to modify neurons within the visual system is restricted to a so-called critical period that, for cats, peaks at about one postnatal month and declines thereafter so that by about 3 months of age MD has little effect. Recovery from the consequences of MD likewise adheres to a critical period that ends by about 3 months of age, after which the effects of deprivation are thought to be permanent and without capacity for reversal...
October 11, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28986534/spatial-scale-of-receptive-fields-in-the-visual-sector-of-the-cat-thalamic-reticular-nucleus
#11
Cristina Soto-Sánchez, Xin Wang, Vishal Vaingankar, Friedrich T Sommer, Judith A Hirsch
Inhibitory projections from the visual sector of the thalamic reticular nucleus to the lateral geniculate nucleus complete the earliest feedback loop in the mammalian visual pathway and regulate the flow of information from retina to cortex. There are two competing hypotheses about the function of the thalamic reticular nucleus. One regards the structure as a thermostat that uniformly regulates thalamic activity through negative feedback. Alternatively, the searchlight hypothesis argues for a role in focal attentional modulation through positive feedback, consistent with observations that behavioral state influences reticular activity...
October 6, 2017: Nature Communications
https://www.readbyqxmd.com/read/28979189/uncorrelated-neural-firing-in-mouse-visual-cortex-during-spontaneous-retinal-waves
#12
Matthew T Colonnese, Jing Shen, Yasunobu Murata
Synchronous firing among the elements of forming circuits is critical for stabilization of synapses. Understanding the nature of these local network interactions during development can inform models of circuit formation. Within cortex, spontaneous activity changes throughout development. Unlike the adult, early spontaneous activity occurs in discontinuous population bursts separated by long silent periods, suggesting a high degree of local synchrony. However, whether the micro-patterning of activity within early bursts is unique to this early age and specifically tuned for early development is poorly understood, particularly within the column...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28973563/nonlinear-dynamics-of-cortical-responses-to-color-in-the-human-cvep
#13
Valerie Nunez, Robert M Shapley, James Gordon
The main finding of this paper is that the human visual cortex responds in a very nonlinear manner to the color contrast of pure color patterns. We examined human cortical responses to color checkerboard patterns at many color contrasts, measuring the chromatic visual evoked potential (cVEP) with a dense electrode array. Cortical topography of the cVEPs showed that they were localized near the posterior electrode at position Oz, indicating that the primary cortex (V1) was the major source of responses. The choice of fine spatial patterns as stimuli caused the cVEP response to be driven by double-opponent neurons in V1...
September 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28965520/the-multifaceted-role-of-inhibitory-interneurons-in-the-dorsal-lateral-geniculate-nucleus
#14
Charles L Cox, Joseph A Beatty
Intrinsic interneurons within the dorsal lateral geniculate nucleus (dLGN) provide a feed-forward inhibitory pathway for afferent visual information originating from the retina. These interneurons are unique because in addition to traditional axodendritic output onto thalamocortical neurons, these interneurons have presynaptic dendrites that form dendrodendritic synapses onto thalamocortical neurons as well. These presynaptic dendrites, termed F2 terminals, are tightly coupled to the retinogeniculate afferents that synapse onto thalamocortical relay neurons...
January 2017: Visual Neuroscience
https://www.readbyqxmd.com/read/28965517/not-a-one-trick-pony-diverse-connectivity-and-functions-of-the-rodent-lateral-geniculate-complex
#15
Aboozar Monavarfeshani, Ubadah Sabbagh, Michael A Fox
Often 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...
January 2017: Visual Neuroscience
https://www.readbyqxmd.com/read/28965507/thalamocortical-processing-in-vision
#16
Reece Mazade, Jose Manuel Alonso
Visual information reaches the cerebral cortex through a major thalamocortical pathway that connects the lateral geniculate nucleus (LGN) of the thalamus with the primary visual area of the cortex (area V1). In humans, ∼3.4 million afferents from the LGN are distributed within a V1 surface of ∼2400 mm2, an afferent number that is reduced by half in the macaque and by more than two orders of magnitude in the mouse. Thalamocortical afferents are sorted in visual cortex based on the spatial position of their receptive fields to form a map of visual space...
January 2017: Visual Neuroscience
https://www.readbyqxmd.com/read/28965501/organization-of-the-dorsal-lateral-geniculate-nucleus-in-the-mouse
#17
Daniel Kerschensteiner, William Guido
The dorsal lateral geniculate nucleus (dLGN) of the thalamus is the principal conduit for visual information from retina to visual cortex. Viewed initially as a simple relay, recent studies in the mouse reveal far greater complexity in the way input from the retina is combined, transmitted, and processed in dLGN. Here we consider the structural and functional organization of the mouse retinogeniculate pathway by examining the patterns of retinal projections to dLGN and how they converge onto thalamocortical neurons to shape the flow of visual information to visual cortex...
January 2017: Visual Neuroscience
https://www.readbyqxmd.com/read/28963811/altered-white-matter-structure-in-the-visual-system-following-early-monocular-enucleation
#18
Nikita A Wong, Sara A Rafique, Krista R Kelly, Stefania S Moro, Brenda L Gallie, Jennifer K E Steeves
Partial visual deprivation from early monocular enucleation (the surgical removal of one eye within the first few years of life) results in a number of long-term morphological adaptations in adult cortical and subcortical visual, auditory, and multisensory brain regions. In this study, we investigated whether early monocular enucleation also results in the altered development of white matter structure. Diffusion tensor imaging and probabilistic tractography were performed to assess potential differences in visual system white matter in adult participants who had undergone early monocular enucleation compared to binocularly intact controls...
September 30, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28945780/whole-brain-high-in-plane-resolution-fmri-using-accelerated-epik-for-enhanced-characterisation-of-functional-areas-at-3t
#19
Seong Dae Yun, N Jon Shah
The relatively high imaging speed of EPI has led to its widespread use in dynamic MRI studies such as functional MRI. An approach to improve the performance of EPI, EPI with Keyhole (EPIK), has been previously presented and its use in fMRI was verified at 1.5T as well as 3T. The method has been proven to achieve a higher temporal resolution and smaller image distortions when compared to single-shot EPI. Furthermore, the performance of EPIK in the detection of functional signals was shown to be comparable to that of EPI...
2017: PloS One
https://www.readbyqxmd.com/read/28922876/visual-deficit-from-laser-interstitial-thermal-therapy-for-temporal-lobe-epilepsy-anatomical-considerations
#20
Walter J Jermakowicz, Michael E Ivan, Iahn Cajigas, Ramses Ribot, Ignacio Jusue-Torres, Mehul B Desai, Armando Ruiz, Pierre-Francois D'Haese, Andres M Kanner, Jonathan R Jagid
BACKGROUND: Laser interstitial thermal therapy (LITT) is quickly emerging as an effective surgical therapy for temporal lobe epilepsy (TLE). One of the most frequent complications of the procedure is postoperative visual field cuts, but the physiopathology of these deficits is unknown. OBJECTIVE: To evaluate potential causes of visual deficits after LITT for TLE in an attempt to minimize this complication. METHODS: This retrospective chart review compares the case of a 24-year-old male who developed homonymous hemianopsia following LITT for TLE to 17 prior patients who underwent the procedure and suffered no visual deficit...
October 1, 2017: Operative Neurosurgery (Hagerstown, Md.)
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