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Fa Yi Xue Za Zhi Aug 2023To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.
OBJECTIVES
To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.
METHODS
Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively.
RESULTS
The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway.
CONCLUSIONS
Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.
Topics: Humans; Optic Chiasm; Visual Pathways; Visual Fields; Evoked Potentials, Visual; Random Amplified Polymorphic DNA Technique; Hemianopsia; Vision Disorders; Optic Nerve Injuries; Brain Injuries, Traumatic
PubMed: 37859473
DOI: 10.12116/j.issn.1004-5619.2023.230309 -
Pediatric Neurology Aug 2018Traumatic visual pathway injuries are often associated with severe head trauma and can have profound deleterious effects in developing children and their rehabilitation....
BACKGROUND
Traumatic visual pathway injuries are often associated with severe head trauma and can have profound deleterious effects in developing children and their rehabilitation. We sought to elucidate the epidemiology of pediatric visual pathway injuries in the United States.
MATERIALS AND METHODS
This study is a retrospective evaluation of pediatric patients (less than 21 years of age) with visual pathway injuries that were submitted to the National Trauma Data Bank between 2008 to 2014. Patients were identified using the International Classification of Diseases, Ninth Revision Clinical Modification codes. Statistical analysis was performed with SPSS software. Variables were correlated using Student t test, chi-squared test, and logistic regression analyses.
RESULTS
Of the 58,765 pediatric patients (1.7%) who were admitted with ocular injuries, 970 had visual pathway injuries. The majority of these patients were male (69.2%), and the mean age was 11.6 years (±7.2). Traumatic optic neuropathy was the most common (86.1%) visual pathway injury. It had the greatest odds of occurring with oculomotor nerve injury (odds ratio = 3.84; P < 0.001). Associated ocular injuries were open adnexal wounds (87.4%) and orbital fractures (23%). Common mechanisms were motor vehicle occupant (21.5%) and firearms (15.6%). Motor vehicle occupants were most likely white and firearms injury, black. In the zero to three years age group, most injuries were due to falls; injuries in the 19 to 21 years age group had the greatest association with firearms. Overall mortality was 17.6%.
CONCLUSIONS
Visual pathway injuries may have devastatating sequelae and should be considered in pediatric ocular injuries. The clear majority were traumatic optic neuropathies. The common mechanisms, motor vehicle occupant and firearms, revealed age and race disparities.
Topics: Adolescent; Child; Child, Preschool; Eye Injuries; Female; Humans; Infant; Infant, Newborn; Male; Retrospective Studies; United States; Visual Pathways; Young Adult
PubMed: 29859721
DOI: 10.1016/j.pediatrneurol.2018.04.003 -
Journal of Physiology, Paris 2003Visual saliency is a fundamental yet hard to define property of objects or locations in the visual world. In a context where objects and their representations compete to... (Review)
Review
Visual saliency is a fundamental yet hard to define property of objects or locations in the visual world. In a context where objects and their representations compete to dominate our perception, saliency can be thought of as the "juice" that makes objects win the race. It is often assumed that saliency is extracted and represented in an explicit saliency map, which serves to determine the location of spatial attention at any given time. It is then by drawing attention to a salient object that it can be recognized or categorized. I argue against this classical view that visual "bottom-up" saliency automatically recruits the attentional system prior to object recognition. A number of visual processing tasks are clearly performed too fast for such a costly strategy to be employed. Rather, visual attention could simply act by biasing a saliency-based object recognition system. Under natural conditions of stimulation, saliency can be represented implicitly throughout the ventral visual pathway, independent of any explicit saliency map. At any given level, the most activated cells of the neural population simply represent the most salient locations. The notion of saliency itself grows increasingly complex throughout the system, mostly based on luminance contrast until information reaches visual cortex, gradually incorporating information about features such as orientation or color in primary visual cortex and early extrastriate areas, and finally the identity and behavioral relevance of objects in temporal cortex and beyond. Under these conditions the object that dominates perception, i.e. the object yielding the strongest (or the first) selective neural response, is by definition the one whose features are most "salient"--without the need for any external saliency map. In addition, I suggest that such an implicit representation of saliency can be best encoded in the relative times of the first spikes fired in a given neuronal population. In accordance with our subjective experience that saliency and attention do not modify the appearance of objects, the feed-forward propagation of this first spike wave could serve to trigger saliency-based object recognition outside the realm of awareness, while conscious perceptions could be mediated by the remaining discharges of longer neuronal spike trains.
Topics: Action Potentials; Animals; Humans; Photic Stimulation; Time Factors; Visual Pathways; Visual Perception
PubMed: 14766152
DOI: 10.1016/j.jphysparis.2003.09.010 -
Zhurnal Voprosy Neirokhirurgii Imeni N.... 2019Sarcoidosis is a multisystem granulomatous disorder of unknown nature. Patients often present with pulmonary, skin, eye, and orbital lesions. Involvement of the central... (Review)
Review
Sarcoidosis is a multisystem granulomatous disorder of unknown nature. Patients often present with pulmonary, skin, eye, and orbital lesions. Involvement of the central nervous system (CNS) is accompanied by granulomatous leptomeningitis and damage to the basal brain structures with formation of granulomas near the cranial nerves, hypothalamus, pituitary gland, cavernous sinuses, optic chiasm, and intracranial optic nerves. The optic nerves can be affected independently of the other CNS regions, which may be the first manifestation of the disease. The article presents two clinical cases of sarcoidosis affecting the anterior visual pathway. Diagnosis of the disease was associated with certain difficulties. A biopsy revealed a sarcoidosis lesion.
Topics: Central Nervous System Diseases; Cranial Nerves; Humans; Sarcoidosis; Visual Pathways
PubMed: 31577275
DOI: 10.17116/neiro20198304197 -
ELife Oct 2023Visual neurons respond selectively to features that become increasingly complex from the eyes to the cortex. Retinal neurons prefer flashing spots of light, primary...
Visual neurons respond selectively to features that become increasingly complex from the eyes to the cortex. Retinal neurons prefer flashing spots of light, primary visual cortical (V1) neurons prefer moving bars, and those in higher cortical areas favor complex features like moving textures. Previously, we showed that V1 simple cell tuning can be accounted for by a basic model implementing temporal prediction - representing features that predict future sensory input from past input (Singer et al., 2018). Here, we show that hierarchical application of temporal prediction can capture how tuning properties change across at least two levels of the visual system. This suggests that the brain does not efficiently represent all incoming information; instead, it selectively represents sensory inputs that help in predicting the future. When applied hierarchically, temporal prediction extracts time-varying features that depend on increasingly high-level statistics of the sensory input.
Topics: Visual Pathways; Motion Perception; Photic Stimulation; Neurons; Brain; Visual Perception
PubMed: 37844199
DOI: 10.7554/eLife.52599 -
Journal of Neurology Mar 2009The afferent visual pathway is commonly affected in MS. Assessment of the afferent visual pathway using clinical, imaging and electrophysiological methods not only... (Review)
Review
The afferent visual pathway is commonly affected in MS. Assessment of the afferent visual pathway using clinical, imaging and electrophysiological methods not only provides insights into the pathophysiology of MS, but also provides a method of investigating potential therapeutic measures in MS. This review summarises the various assessment methods, in particular imaging techniques of the visual pathway. Retinal nerve fibre layer (RNFL) thickness is usually reduced following an episode of optic neuritis. Techniques such as optical coherence tomography, scanning laser polarimetry, and confocal scanning laser ophthalmoscopy are used to quantify RNFL thickness. MRI of the optic nerve is not routinely used in the diagnosis of MS or optic neuritis, but is valuable in atypical cases and in research. T2- weighted images of the optic nerve usually show the hyperintense lesion in optic neuritis and gadolinium enhancement is seen in the acute attack. Quantifying atrophy of the optic nerve using MRI gives an indication of the degree of axonal loss. Magnetization transfer ratio (MTR) of the optic nerve provides an indication of myelination. Diffusion tensor imaging (DTI) of the optic nerve and optic radiation provide information about the integrity of the visual white matter tracts. Functional MRI following visual stimulation is used to assess the contribution of cortical reorganisation to functional recovery following optic neuritis. Investigations including logMAR visual acuity, Sloan contrast acuity, Farnsworth- Munsell 100-hue colour vision tests and Humphrey perimetry provide detailed quantitative information on different aspects of visual function. Visual evoked potentials identify conduction block or delay reflecting demyelination. These collective investigative methods have advanced knowledge of pathophysiological mechanisms in MS and optic neuritis. Relevant ongoing studies and future directions are discussed.
Topics: Afferent Pathways; Atrophy; Brain; Diagnostic Imaging; Evoked Potentials, Visual; Humans; Multiple Sclerosis; Neuropsychological Tests; Optic Nerve; Optic Neuritis; Retina; Visual Pathways
PubMed: 19296047
DOI: 10.1007/s00415-009-0123-z -
NeuroImage Oct 2020The extrastriate cortex in the human visual cortex is divided into two distinct clusters: the "what-information" processing area and the "where-information" processing...
The extrastriate cortex in the human visual cortex is divided into two distinct clusters: the "what-information" processing area and the "where-information" processing area. It is widely accepted that the "what-information" cluster is processed through the ventral stream to the temporal cortex, and the "where-information" cluster through the dorsal stream to the parietal cortex. In human neuroanatomy, fiber bundles for the ventral stream (such as the inferior longitudinal fasciculus) are well defined, whereas fibers for the dorsal stream are poorly understood. In this study, we attempted to trace the dorsal stream fibers using a fiber tracking method using 7.0T diffusion-weighted MRI. We used data from a healthy male subject as well as from an unbiasedly selected nine-subject dataset in the Human Connectome Project. The surface of the visual area, including V1, V2, V3, V4, MT, was determined from the Brainnetome atlas (Fan et al., 2016), which is the connectivity-based parcellation framework of the human brain. The resulting visual pathway indicated that the putative pathway for the classical dorsal stream is unlikely to exist. Instead, we demonstrated that fiber connections exist between the angular gyrus with MT in the visual cortex, and between the angular gyrus and IT in the temporal cortex. Through that, we composed a two-pathway model for where-information processing that passes through the angular gyrus. Finally, we proposed a modified human visual pathway model based on our fiber tracking results in this report. The modified where-information pathway will provide a new aspect for the study of human visual processing.
Topics: Brain Mapping; Connectome; Diffusion Magnetic Resonance Imaging; Humans; Parietal Lobe; Visual Cortex; Visual Pathways
PubMed: 32650055
DOI: 10.1016/j.neuroimage.2020.117145 -
Child's Nervous System : ChNS :... Apr 2018Bevacizumab (BVZ) is a vascular endothelial growth factor inhibitor that has been widely accepted since its introduction into the cancer pharmacopoeia. Anecdotal reports... (Review)
Review
BACKGROUND
Bevacizumab (BVZ) is a vascular endothelial growth factor inhibitor that has been widely accepted since its introduction into the cancer pharmacopoeia. Anecdotal reports suggested improvements in vision in children with visual pathway glioma.
CASE PRESENTATION
We report a boy with visual pathway glioma whose vision had deteriorated significantly on vincristine and carboplatin, to the point that he was registered blind. Following bevacizumab therapy, there was a dramatic improvement in vision with reduction in tumour volume. However, following 20 doses of BVZ given over 19 months, he developed a significant cerebrovascular stenosis.
CONCLUSION
The BVZ-induced cerebrovascular diseases in children are extremely rare but potentially serious. Importantly, stenosis has not been previously described in literature.
Topics: Antineoplastic Agents, Immunological; Bevacizumab; Brain Neoplasms; Child, Preschool; Constriction, Pathologic; Humans; Magnetic Resonance Angiography; Magnetic Resonance Imaging; Male; Optic Nerve Glioma; Visual Pathways
PubMed: 29249070
DOI: 10.1007/s00381-017-3676-7 -
Annual Review of Vision Science Sep 2019With modern neurophysiological methods able to record neural activity throughout the visual pathway in the context of arbitrarily complex visual stimulation, our... (Review)
Review
With modern neurophysiological methods able to record neural activity throughout the visual pathway in the context of arbitrarily complex visual stimulation, our understanding of visual system function is becoming limited by the available models of visual neurons that can be directly related to such data. Different forms of statistical models are now being used to probe the cellular and circuit mechanisms shaping neural activity, understand how neural selectivity to complex visual features is computed, and derive the ways in which neurons contribute to systems-level visual processing. However, models that are able to more accurately reproduce observed neural activity often defy simple interpretations. As a result, rather than being used solely to connect with existing theories of visual processing, statistical modeling will increasingly drive the evolution of more sophisticated theories.
Topics: Humans; Machine Learning; Models, Neurological; Nerve Net; Neurons; Visual Cortex; Visual Pathways
PubMed: 31386605
DOI: 10.1146/annurev-vision-091718-014731 -
Clinical & Experimental Ophthalmology Jan 2017Multiple sclerosis (MS) is a disease of the central nervous system that involves inflammation and demyelination at multiple sites and causes a wide variety of clinical... (Review)
Review
Multiple sclerosis (MS) is a disease of the central nervous system that involves inflammation and demyelination at multiple sites and causes a wide variety of clinical presentations with variable neurological deficits. The visual pathways are frequently involved with either visual or motor dysfunction. Optic neuritis (ON) is one the most common and best characterized presentations of the disease, but there are many other manifestations depending on the site of the lesion. Eyes that have never had ON show slow progressive loss of axons and retinal ganglion cells. Previously unrecognized optic radiation lesions may be associated with residual latency delays on visual evoked potentials. Both anterograde and retrograde degeneration may occur along the visual pathway. This review covers the features of MS in the anterior and posterior visual system and describes advances that have been made with newer techniques such as retinal optical coherence tomography (OCT), magnetic resonance imaging (MRI) with diffusion tensor imaging and probabilistic tractography (DTI) and multifocal visual evoked potentials (mfVEPs). We report on the inter-relationship between these measures of structure and function, and how they may be used as biomarkers for the disease.
Topics: Afferent Pathways; Diffusion Tensor Imaging; Evoked Potentials, Visual; Humans; Magnetic Resonance Imaging; Multiple Sclerosis; Nerve Fibers; Optic Neuritis; Retinal Ganglion Cells; Tomography, Optical Coherence; Visual Pathways
PubMed: 27011293
DOI: 10.1111/ceo.12751