Axonal Injury in the Lateral Geniculate Body: Radiological Diagnosis.
Ontology highlight
ABSTRACT:
SUBMITTER: Gutierrez L
PROVIDER: S-EPMC5762140 | biostudies-literature | 2017 Aug
REPOSITORIES: biostudies-literature
Publications
Axonal Injury in the Lateral Geniculate Body: Radiological Diagnosis.
Gutiérrez Laura L Arruga Jorge J Sánchez Juan J JJ Muñoz Silvia S Puyalto-de-Pablo Paloma P
Neuro-ophthalmology (Aeolus Press) 20170309 4
Damage to the lateral geniculate body by diffuse axonal injury in brain trauma is uncommon. The authors present the clinical case and <i>in vivo</i> fibre tractography using diffusion tensor magnetic resonance imaging of this lesion in a patient presenting with homonymous sectoranopia after a traumatic head injury. ...[more]
Similar Datasets
Project description:Injury to the primary visual cortex (V1) leads to the loss of visual experience. Nonetheless, careful testing shows that certain visually guided behaviours can persist even in the absence of visual awareness. The neural circuits supporting this phenomenon, which is often termed blindsight, remain uncertain. Here we demonstrate that the thalamic lateral geniculate nucleus (LGN) has a causal role in V1-independent processing of visual information. By comparing functional magnetic resonance imaging (fMRI) and behavioural measures with and without temporary LGN inactivation, we assessed the contribution of the LGN to visual functions of macaque monkeys (Macaca mulatta) with chronic V1 lesions. Before LGN inactivation, high-contrast stimuli presented to the lesion-affected visual field (scotoma) produced significant V1-independent fMRI activation in the extrastriate cortical areas V2, V3, V4, V5/middle temporal (MT), fundus of the superior temporal sulcus (FST) and lateral intraparietal area (LIP) and the animals correctly located the stimuli in a detection task. However, following reversible inactivation of the LGN in the V1-lesioned hemisphere, fMRI responses and behavioural detection were abolished. These results demonstrate that direct LGN projections to the extrastriate cortex have a critical functional contribution to blindsight. They suggest a viable pathway to mediate fast detection during normal vision.
| S-EPMC2904843 | biostudies-literature
Project description:A key task for the visual system is to combine spatially overlapping representations of the environment, viewed by either eye, into a coherent image. In cats and primates, this is accomplished in the cortex [1], with retinal outputs maintained as separate monocular maps en route through the lateral geniculate nucleus (LGN). While this arrangement is also believed to apply to rodents [2, 3], this has not been functionally confirmed. Accordingly, here we used multielectrode recordings to survey eye-specific visual responses across the mouse LGN. Surprisingly, while we find that regions of space visible to both eyes do indeed form part of a monocular representation of the contralateral visual field, we find no evidence for a corresponding ipsilateral representation. Instead, we find many cells that can be driven via either eye. These inputs combine to enhance the detection of weak stimuli, forming a binocular representation of frontal visual space. This extensive thalamic integration marks a fundamental distinction in mechanisms of binocular processing between mice and other mammals.
| S-EPMC4046226 | biostudies-literature
Project description:The lateral geniculate nucleus (LGN) of catarrhine primates - with the exception of gibbons - is typically described as a 6-layered structure, comprised of 2 ventral magnocellular layers, and 4 dorsal parvocellular layers. The parvocellular layers of the LGN are involved in color vision. Therefore, it is hypothesized that a 6-layered LGN is a shared-derived trait among catarrhines. This might suggest that in gibbons the lack of further subdivisions of the parvocellular layers is a recent change, and could be related to specializations of visual information processing in this taxon. To address these hypotheses, the lamination of the LGN was investigated in a range of catarrhine species, including several taxa not previously described, and the evolution of the LGN was reconstructed using phylogenetic information. The findings indicate that while all catarrhine species have 4 parvocellular leaflets, two main patterns of LGN parvocellular lamination occur: 2 undivided parvocellular layers in some species, and 4 parvocellular leaflets (with occasional subleaflets) in other species. LGN size was not found to be related to lamination pattern. Both patterns were found to occur in divergent clades, which is suggestive of homoplasy within the catarrhines in LGN morphology.
| S-EPMC3741618 | biostudies-literature
Project description:Introduction:Giant axonal neuropathy (GAN) is an inherited neurodegenerative disorder caused by mutations in the GAN gene. It affects both the central and peripheral nervous systems. We discuss clinical, electrophysiological, radiological and genetic features in three new unrelated patients with GAN. Methods:Three pediatric patients with suspected GAN were included. The diagnosis was considered in patients with early onset polyneuropathy and characteristic hair with central nervous system involvement or suggestive neuroimaging findings. Biochemical, metabolic and electrophysiological investigations were performed. Diagnosis was confirmed by targeted sequencing of the GAN gene. Results:All the three patients were found to have biallelic mutations in GAN gene. Peripheral neuropathy, characteristic hair, and cerebellar dysfunction were present in all three while bony deformities, cranial nerve involvement and intellectual disability were seen variably. Neuroimaging showed a spectrum of findings which are discussed. Conclusion:GAN is a clinically and radiologically heterogeneous disease where genetic testing is necessary for a definite diagnosis and counselling. With facilities for testing becoming increasingly available, the spectrum is likely to expand further.
| S-EPMC6238561 | biostudies-literature
Project description:The mammalian visual system is one of the most well-studied brain systems. Visual information from the retina is relayed to the dorsal lateral geniculate nucleus of the thalamus (LGd). The LGd then projects topographically to primary visual cortex (VISp) to mediate visual perception. In this view, the VISp is a critical network hub where visual information must traverse LGd-VISp circuits to reach higher order "extrastriate" visual cortices, which surround the VISp on its medial and lateral borders. However, decades of conflicting reports in a variety of mammals support or refute the existence of extrastriate LGd connections that can bypass the VISp. Here, we provide evidence of bidirectional extrastriate connectivity with the mouse LGd. Using small, discrete coinjections of anterograde and retrograde tracers within the thalamus and cortex, our cross-validated approach identified bidirectional connectivity between LGd and extrastriate visual cortices. We find robust reciprocal connectivity of the medial extrastriate regions with LGd neurons distributed along the "ventral strip" border with the intergeniculate leaflet. In contrast, LGd input to lateral extrastriate regions is sparse, but lateral extrastriate regions return stronger descending projections to localized LGd areas. We show further evidence that axons from lateral extrastriate regions can overlap onto medial extrastriate-projecting LGd neurons in the ventral strip, providing a putative subcortical LGd pathway for communication between medial and lateral extrastriate regions. Overall, our findings support the existence of extrastriate LGd circuits and provide novel understanding of LGd organization in rodent visual system.
| S-EPMC6992387 | biostudies-literature
Project description:Orientation selectivity is a cornerstone property of vision, commonly believed to emerge in the primary visual cortex. We found that reliable orientation information could be detected even earlier, in the human lateral geniculate nucleus, and that attentional feedback selectively altered these orientation responses. This attentional modulation may allow the visual system to modify incoming feature-specific signals at the earliest possible processing site.
| S-EPMC4556110 | biostudies-literature
Project description:Laser capture microdissection was used to obtain individual LGN layers for DNA microarray in macaque monkeys that underwent monocular eyelid suture at birth.
2008-06-11 | E-GEOD-2165 | biostudies-arrayexpress
Project description:When dissimilar images are presented to the two eyes, they compete for perceptual dominance so that only one image is visible at a time while the other one is suppressed. Neural correlates of such binocular rivalry have been found at multiple stages of visual processing, including striate and extrastriate visual cortex. However, little is known about the role of subcortical processing during binocular rivalry. Here we used fMRI to measure neural activity in the human LGN while subjects viewed contrast-modulated gratings presented dichoptically. Neural activity in the LGN correlated strongly with the subjects' reported percepts, such that activity increased when a high-contrast grating was perceived and decreased when a low-contrast grating was perceived. Our results provide evidence for a functional role of the LGN in binocular rivalry and suggest that the LGN, traditionally viewed as the gateway to the visual cortex, may be an early gatekeeper of visual awareness.
| S-EPMC1470662 | biostudies-literature
Project description:We show functional-anatomical organization of motion direction in mouse dorsal lateral geniculate nucleus (dLGN) using two-photon calcium imaging of dense populations in thalamus. Surprisingly, the superficial 75 ?m region contains anterior and posterior direction-selective neurons (DSLGNs) intermingled with nondirection-selective neurons, while upward- and downward-selective neurons are nearly absent. Unexpectedly, the remaining neurons encode both anterior and posterior directions, forming horizontal motion-axis selectivity. A model of random wiring consistent with these results makes quantitative predictions about the connectivity of direction-selective retinal ganglion cell (DSRGC) inputs to the superficial dLGN. DSLGNs are more sharply tuned than DSRGCs. These results suggest that dLGN maintains and sharpens retinal direction selectivity and integrates opposing DSRGC subtypes in a functional-anatomical region, perhaps forming a feature representation for horizontal-axis motion, contrary to dLGN being a simple relay. Furthermore, they support recent conjecture that cortical direction and orientation selectivity emerge in part from a previously undescribed motion-selective retinogeniculate pathway.
| S-EPMC3517882 | biostudies-literature
Project description:Relay neurons in the dorsal lateral geniculate nucleus (dLGN) receive excitatory inputs from retinal ganglion cells (RGCs). Retinogeniculate synapses are characterized by a prominent short-term depression of AMPA receptor (AMPAR)-mediated currents, but the underlying mechanisms and its function for visual integration are not known. Here we identify CKAMP44 as a crucial auxiliary subunit of AMPARs in dLGN relay neurons, where it increases AMPAR-mediated current amplitudes and modulates gating of AMPARs. Importantly, CKAMP44 is responsible for the distinctive short-term depression in retinogeniculate synapses by reducing the rate of recovery from desensitization of AMPARs. Genetic deletion of CKAMP44 strongly reduces synaptic short-term depression, which leads to increased spike probability of relay neurons when activated with high-frequency inputs from retinogeniculate synapses. Finally, in vivo recordings reveal augmented ON- and OFF-responses of dLGN neurons in CKAMP44 knockout (CKAMP44-/-) mice, demonstrating the importance of CKAMP44 for modulating synaptic short-term depression and visual input integration.
| S-EPMC5772470 | biostudies-literature