A direct afferent visual pathway from the nucleus of the optic tract to the inferior olive in the cat.
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Afferent Pathways↗
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Infantile cerebral aneurysms with visual pathway compression.
Intracranial aneurysms are rare in infancy. The commonest presentation is intracranial hemorrhage, but signs of mass effect are more frequent than in adults. We report 2 infants with cerebral aneurysms, one presenting with macrocephaly and another with strabismus. Both had visual loss and optic disc pallor; MRI revealed a suprasellar mass and anterior visual pathway compression. In both cases, the preoperative diagnosis was craniopharyngioma. It is essential to recognize that, although exceedingly uncommon, cerebral aneurysms do occur in infants and have features that differ from those in adults.
Calcinosis↗
The prevalence of strabismus in congenital nystagmus: the influence of anterior visual pathway disease.
PURPOSE: To determine the influence of underlying visual system disorders on the risk of developing strabismus in children with congenital nystagmus. METHODS: We retrospectively reviewed 82 cases of congenital nystagmus from a pediatric ophthalmology referral practice. RESULTS: Strabismus was found in 50% of children with congenital nystagmus. The prevalence of strabismus was 82% in children with bilateral optic nerve hypoplasia, 53% in patients with albinism, 36% in children with congenital retinal dystrophies, and 17% in children with idiopathic congenital nystagmus. CONCLUSION: The risk that a child with congenital nystagmus will have strabismus develop can be predicted from the nature of the underlying visual disorder.
Adolescent↗
[Long-term outcome of gliomas of the visual pathway in type 1 neurofibromatosis].
BACKGROUND: Optic gliomas are frequently associated with neurofibromatosis type 1 (NF1) and belong to the diagnostic criteria of NF1. Different growth rates require differentiated strategies for screening and observation. PATIENTS AND METHODS: 29 patients (25 children < 11 years, 4 adults > 18 years) with visual pathway tumors and NF1 were examined neurologically, ophthalmogically, by means of MRI and VEP. Results were set into context with preceding investigations (mean follow up time 6.5 years). RESULTS: 11 children showed a stable condition, 14 an unfavorable process with substantial loss of vision. Children with an unfavorable process showed a lower age at diagnosis (3.2 versus 5.8 years; p < 0.05), more frequently strabism (11/14 versus 1/11; p < 0.05), optic atrophy (12/14 versus 1/11; p < 0.05), pathological VEP (9/9 versus 2/10; p = 0.001), visual field defects (9/9 versus 1/9) and involvement of the optic chiasm (11/14 versus 3/11; p < 0.05) than children with a stable condition. 3 of 4 adults had no visual symptoms despite involvement of the optic chiasm. CONCLUSIONS: The crucial prognostic factor is the patient's age at the time of diagnosis. Optic gliomas which become symptomatic in early childhood (< 6 years) grow rapidly and require frequent ophthalmologic investigations and MRI. Tumors diagnosed in late childhood (> 6 years) do not progress, allowing for gradual extension of intervals between ophthalmological investigations.
Adolescent↗
Visual intensity and pattern discrimination after lesions of the thalamofugal visual pathway in pigeons.
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Animals↗
On the structure and function of the tectofugal visual pathway in laterally eyed birds.
Of the two visual systems in vertebrates, the tectofugal pathway has often been attributed to stimulus localization, while the thalamofugal pathway was thought to be involved in stimulus identification. This review provides evidence that the tectofugal pathway serves both functions. It is speculated that the initial task of the tectum is to localize an object and to guide the fixation movement. The object in focus is then analysed by the higher stations of the tectofugal system. The result of the analysis is fed into the optic tectum and is used for decision about the treatment of the object.
Animals↗
Proteins of visual pathways having varied retinal receptors in altered conditions of visual stimuli.
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Animals↗
Spatial characteristics of movement detection mechanisms in human vision. III. Subjects with abnormal visual pathways.
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Adult↗
Myelin repair by Schwann cells in the regenerating goldfish visual pathway: regional patterns revealed by X-irradiation.
In the regenerating goldfish optic nerves, Schwann cells of unknown origin reliably infiltrate the lesion site forming a band of peripheral-type myelinating tissue by 1-2 months, sharply demarcated from the adjacent new CNS myelin. To investigate this effect, we have interfered with cell proliferation by locally X-irradiating the fish visual pathway 24h after the lesion. As assayed by immunohistochemistry and EM, irradiation retards until 6 months formation of new myelin by Schwann cells at the lesion site, and virtually abolishes oligodendrocyte myelination distally, but has little or no effect on nerve fibre regrowth. Optic nerve astrocyte processes normally fail to re-infiltrate the lesion, but re-occupy it after irradiation, suggesting that they are normally excluded by early cell proliferation at this site. Moreover, scattered myelinating Schwann cells also appear in the oligodendrocyte-depleted distal optic nerve after irradiation, although only as far as the optic tract. Optic nerve reticular astrocytes differ in various ways from radial glia elsewhere in the fish CNS, and our observations suggest that they may be more permissive to Schwann cell invasion of CNS tissue.
Animals↗
Normal visual pathway routing in dissociated vertical deviation.
Flash visually evoked cortical potentials have been recorded in three groups of age- and sex-matched subjects; one comprised of subjects with dissociated vertical deviation, one comprised of subjects with oculocutaneous albinism and one group of controls. The latency of the major positive (P2) component did not show statistically significant contralateral lateralization on monocular stimulation in either the dissociated vertical deviation group or the control group. Contralateral lateralization was found in the albino group at a statistically significant level (P less than 0.01). It is concluded that subjects with dissociated vertical deviation do not possess the typical albino optic pathway misrouting that has been reported.
Adolescent↗
Evidence for spatial aliasing effects in the Y-like cells of the magnocellular visual pathway.
Several lines of evidence are provided indicating that our visual percept can be dominated by spatial aliasing for viewing conditions near those needed to see the spatial frequency doubled illusion. The apparent aliasing effect indicates that the underlying sampling array has a density 15-30% of that of M-cells, in agreement with the known proportion of Y-like M-cells (M(y)-cells). The presence of aliasing indicates, that there is a separate irregular array of M(y)-cells, and that their role is to rapidly convey information on retinal gain control to the brain rather than to act primarily as inputs to image motion computation.
Adaptation, Ocular↗
[Multifocal ischemic lesions of the visual pathways (author's transl)].
Multiple ischemic lesions of the optic pathways may cause a number of complex visual field defects; their analysis is of substantial diagnostic significance, especially if the computer tomogram is negative. Perimetry is often complicated by an accompanying organic psychosyndrome.
Carotid Artery Diseases↗
[Representation of the visual pathways in the retrosplenial area of the rat limbic cortex].
Visual inputs to field 29 of the limbic retrosplenial cortex have been studied by means of paired stimuli, i.e. photic and electrical stimulation of the anterodorsal nucleus (ADN). During stimulation of this nucleus, the evoked potentials in the field 29 decreased in the initial phase of visual stimulation, indicating the involvement of the ADN into the visual system. This finding confirms earlier morphological data [2]. Besides this, in the field 29 neurones were found which responded to light but not to ADN stimulation, suggesting the possibility of termination of different visual inputs on the neurones of the limbic cortex.
Animals↗
Network analysis of cortical visual pathways mapped with PET.
Brain metabolic mapping techniques, such as positron emission tomography (PET), can provide information about the functional interactions within entire neural systems. With the large quantity of data that can accumulate from a mapping study, a network analysis, which makes sense of the complex interactions among neural elements, is necessary. A network analysis was performed on data obtained from a PET study that examined both the changes in regional cerebral blood flow (rCBF) and interregional correlations among human cortical areas during performance of an object vision (face matching) and spatial vision (dot-location matching) task. Brain areas for the network were selected based on regions showing significant rCBF or interregional correlations between tasks. Anterior temporal and frontal lobe regions were added to the network using a principal components analysis. Interactions among selected regions were quantified with structural equation modeling. In the structural equation models, connections between brain areas were based on known neuroanatomy and the interregional correlations were used to calculate path coefficients representing the magnitude of the influence of each directional path. The combination of the anatomical network and interregional correlations created a functional network for each task. The functional network for the right hemisphere showed that in the object vision task, dominant path influences were among occipitotemporal areas, while in the spatial vision task, occipitoparietal interactions were stronger. The network for the spatial vision task also had a strong feedback path from area 46 to occipital cortex, an effect that was absent in the object vision task. There were strong interactions between dorsal and ventral pathways in both networks. Functional networks for the left hemisphere did not differ between tasks. Networks for the interhemispheric interactions showed that the dominant pathway in the right hemisphere also had stronger effects on homologous left hemisphere areas and are consistent with a hypothesis that intrahemispheric interactions were greater in the right hemisphere in both tasks, and that these influences were transmitted callosally to the left hemisphere.
Adult↗
Network analysis of PET-mapped visual pathways in Alzheimer type dementia.
Using path analysis to determine the systems-level neural networks mediating specific tasks from regional cerebral blood flow (rCBF) data obtained by positron emission tomography (PET), we recently found in young subjects strong functional linkages during a face matching task along a right hemisphere ventral network including occipital, temporal, and frontal regions. In this study, PET data obtained during a face matching task from mildly affected patients with dementia of the Alzheimer type (DAT) and healthy matched controls showed that (1) the neural model obtained in young subjects provides a good fit to data from old subjects; (2) although the DAT patients could perform this task with the same accuracy as controls, they did not use the same functional network.
Aged↗
Migration of ribosomes along the axons of the chick visual pathway.
The axoplasmic migration of ribosomes has been detected in the visual system of the chick. Monocular injection of radioactive uridine or an amino acid mixture was followed by sedimentation analysis in sucrose or cesium sulfate density gradients, of ribosomes prepared from the retinae of injected eyes and the left and right optic lobes. By this means both RNA and protein components of ribosomes were found to migrate from the retina to the innervated contralateral optic lobe. Following denervation of the distal nerve segment by eye removal, the stability of the transported RNA was reduced, suggesting its presynaptic location. The transport of RNA was not significantly imparied by intraocular injection of inhibitors of informational RNA or mitochondrial RNA synthesis prior to injection of radioactive uridine but was depressed by a low dose of actinomycin D.
Amanitins↗