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Klinische Monatsblatter Fur... Nov 2017Precise knowledge of the neuroanatomy of the visual system including the perception of visual stimuli in the retina, the transmission of visual information to other... (Review)
Review
Precise knowledge of the neuroanatomy of the visual system including the perception of visual stimuli in the retina, the transmission of visual information to other areas of the central nervous system and the processing of visual information, are most important for diagnostics of diseases, which are affecting this system. Such knowledge allows, even after just a clinical examination, already a quite precise localisation of potential lesions. The aim of this article is to illustrate the neuroanatomy of the visual system with the focus on the visual pathway and the processing of visual information. Next to the main visual pathway, also other retinofugal projections are discussed. Domains, which are important for the oculomotor system, are discussed in another article in this edition of the journal.
Topics: Brain Mapping; Dominance, Cerebral; Geniculate Bodies; Humans; Interneurons; Nerve Fibers; Neurons; Optic Nerve; Optic Tract; Retina; Visual Cortex; Visual Fields; Visual Pathways; Visual Perception
PubMed: 29155433
DOI: 10.1055/s-0043-118101 -
Neuropsychologia Aug 2016Visual motion processing is often attributed to the dorsal visual pathway despite visual motion's involvement in almost all visual functions. Furthermore, some visual... (Review)
Review
Visual motion processing is often attributed to the dorsal visual pathway despite visual motion's involvement in almost all visual functions. Furthermore, some visual motion tasks critically depend on the structural integrity of regions outside the dorsal pathway. Here, based on numerous studies, I propose that visual motion signals are swiftly transmitted via multiple non-hierarchical routes to primary motion-dedicated processing regions (MT/V5 and MST) that are not part of the dorsal pathway, and then propagated to a multiplicity of brain areas according to task demands, reaching these regions earlier than the dorsal/ventral hierarchical flow. This not only places MT/V5 at the same or even earlier visual processing stage as that of V1, but can also elucidate many findings with implications to visual awareness. While the integrity of the non-hierarchical motion pathway is necessary for all visual motion perception, it is insufficient on its own, and the transfer of visual motion signals to additional brain areas is crucial to allow the different motion perception tasks (e.g. optic flow, visuo-vestibular balance, movement observation, dynamic form detection and perception, and even reading). I argue that this lateral visual motion pathway can be distinguished from the dorsal pathway not only based on faster response latencies and distinct anatomical connections, but also based on its full field representation. I also distinguish between this primary lateral visual motion pathway sensitive to all motion in the visual field, and a much less investigated optic flow sensitive medial processing pathway (from V1 to V6 and V6A) that appears to be part of the dorsal pathway. Multiple additional predictions are provided that allow testing this proposal and distinguishing between the visual pathways.
Topics: Humans; Motion; Motion Perception; Visual Pathways
PubMed: 27444880
DOI: 10.1016/j.neuropsychologia.2016.07.018 -
Seminars in Ultrasound, CT, and MR Oct 2014Visual failure of any kind is a common clinical presentation and indication for neuroimaging. Monocular deficits should concentrate the search to the anterior... (Review)
Review
Visual failure of any kind is a common clinical presentation and indication for neuroimaging. Monocular deficits should concentrate the search to the anterior (prechiasmatic) visual pathway. Bitemporal hemianopia suggests a chiasmatic cause, whereas retrochiasmatic lesions characteristically cause homonymous hemianopic defects. Quadrantanopias usually arise from lesions in the optic radiations. Disorders of visual perception can be broadly divided into "where" and "what" problems caused by lesions in the parietal and temporal lobes, respectively, and their associated white matter tracts. Visualization of the retrochiasmatic visual and visual association pathways is aided by diffusion tensor imaging.
Topics: Humans; Models, Anatomic; Models, Neurological; Vision Disorders; Visual Cortex; Visual Pathways; Visual Perception; White Matter
PubMed: 25217301
DOI: 10.1053/j.sult.2014.06.007 -
Survey of Ophthalmology 2022There is a strong interrelationship between eye and brain diseases. It has been shown that neurodegenerative changes can spread bidirectionally in the visual pathway... (Review)
Review
There is a strong interrelationship between eye and brain diseases. It has been shown that neurodegenerative changes can spread bidirectionally in the visual pathway along neuronal projections. For example, damage to retinal ganglion cells in the retina leads to degeneration of the visual cortex (anterograde degeneration) and vice versa (retrograde degeneration). The underlying mechanisms of this process, known as trans-synaptic degeneration (TSD), are unknown, but TSD contributes to the progression of numerous neurodegenerative disorders, leading to clinical and functional deterioration. The hierarchical structure of the visual system comprises of a strong topographic connectivity between the retina and the visual cortex and therefore serves as an ideal model to study the cellular effect, clinical manifestations, and deterioration extent of TSD. With this review we provide comprehensive information about the neural connectivity, synapse function, molecular changes, and pathophysiology of TSD in visual pathways. We then discuss its bidirectional nature and clinical implications in neurodegenerative diseases. A thorough understanding of TSD in the visual pathway can provide insights into progression of neurodegenerative disorders and its potential as a therapeutic target.
Topics: Humans; Neurodegenerative Diseases; Retinal Ganglion Cells; Retrograde Degeneration; Synapses; Visual Pathways
PubMed: 34146577
DOI: 10.1016/j.survophthal.2021.06.001 -
Trends in Neurosciences Jan 2015Sensory systems project information in a highly organized manner to the brain, where it is preserved in maps of the sensory structures. These sensory projections are... (Review)
Review
Sensory systems project information in a highly organized manner to the brain, where it is preserved in maps of the sensory structures. These sensory projections are altered in congenital abnormalities, such as anophthalmia, albinism, achiasma, and hemihydranencephaly. Consequently, these abnormalities, profoundly affect the organization of the visual system. Surprisingly, visual perception remains largely intact, except for anophthalmia. Recent brain imaging advances shed light on the mechanisms that underlie this phenomenon. In contrast to animal models, in humans the plasticity of thalamocortical connections appears limited, thus demonstrating the importance of cortical adaptations. We suggest that congenital visual pathway abnormalities provide a valuable model to investigate the principles of plasticity that make visual representations available for perception and behavior in humans.
Topics: Animals; Humans; Neuronal Plasticity; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 25448619
DOI: 10.1016/j.tins.2014.09.005 -
Multiple Sclerosis (Houndmills,... Nov 2014Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant.... (Review)
Review
Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant. The visual pathway represents a model of acute focal central nervous system (CNS) damage, through acute optic neuritis and retinal periphlebitis, as well as a model of chronic, diffuse CNS damage through chronic retinopathy and optic neuropathy. The optic pathway can be accurately evaluated in detail, due to the availability of highly sensitive imaging techniques (e.g. magnetic resonance imaging or optical coherent tomography) or electrophysiological tests (multifocal visual evoked potentials or electroretinography). These techniques allow the interactions between the different processes at play to be evaluated, such as inflammation, demyelination, axonal damage and neurodegeneration. Moreover, these features mean that the visual pathway can be used as a model to test new neuroprotective or regenerative therapies.
Topics: Animals; Brain; Evoked Potentials, Visual; Humans; Multiple Sclerosis; Visual Pathways
PubMed: 25013155
DOI: 10.1177/1352458514542862 -
Identification of posterior visual pathway lesions and MRI burden in people with Multiple Sclerosis.Neurosciences (Riyadh, Saudi Arabia) Apr 2021This review systematically identifies posterior visual pathway lesions and MRI burden in people with multiple sclerosis (MS). (Review)
Review
OBJECTIVES
This review systematically identifies posterior visual pathway lesions and MRI burden in people with multiple sclerosis (MS).
METHODS
The articles were searched through Web of Science, Medline, and Embase databases on January 2020, for English language articles from 2000 to 2019.
RESULTS
This review presents summary measures if related to MRI assessment to an overall measure of MS and visual pathway lesions. A total of 44 articles fulfilled all inclusion criteria, covering the period 2000-2019. Different atypical outcomes reveal a low risk for subsequent clinically predefined MS development, specifically in the presence of normal brain MRI. Several impairments related to quality of life have been identified as a result of the effect of retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer.
CONCLUSION
The afferent visual system in MS offers unique accessibility and structure-related functions with further understanding offered by electrophysiology, considering vision as a useful framework for examining new multiple sclerosis therapies.
Topics: Humans; Magnetic Resonance Imaging; Multiple Sclerosis; Visual Pathways
PubMed: 33814364
DOI: 10.17712/nsj.2021.2.20200048 -
Current Medical Science Dec 2018With an increasing incidence, diabetic retinopathy is one of the most important complications of diabetes mellitus (DM) and is also known as one of the major reasons of... (Review)
Review
With an increasing incidence, diabetic retinopathy is one of the most important complications of diabetes mellitus (DM) and is also known as one of the major reasons of adult acquired blindness. It is widely accepted that the visual impairment of diabetic patients results from retinal microvascular changes. However, recent clinical experimental and neuroimaging studies suggest that the visual impairment of diabetic patients is also related to the pathophysiological changes of different parts of the visual pathway in diabetic retinopathy. Therefore, the magnetic resonance imaging (MRI) techniques have been widely used for evaluating the microstructural changes, white matter integrity, metabolite changes, and the whole or partial functional and anatomic changes in the diabetic retinopathy patients' brains in order to fully understand the mechanism of vision loss of the diabetic retinopathy patients. This review focuses on the research progress in application of MRI of the visual pathway in diabetic retinopathy.
Topics: Animals; Blindness; Diabetic Retinopathy; Humans; Magnetic Resonance Imaging; Visual Pathways
PubMed: 30536057
DOI: 10.1007/s11596-018-1971-5 -
Der Ophthalmologe : Zeitschrift Der... Nov 2020
Topics: Auditory Pathways; Humans; Photic Stimulation; Visual Pathways; Visual Perception
PubMed: 33151435
DOI: 10.1007/s00347-020-01082-w -
Neurosurgical Review Apr 2018The objective of this systematic literature review is to assess the role of retinal optical coherence tomography (OCT) in the evaluation of patients with tumors of the... (Review)
Review
The objective of this systematic literature review is to assess the role of retinal optical coherence tomography (OCT) in the evaluation of patients with tumors of the visual pathway. We performed a PubMed database search according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search was restricted to articles published in English between 2000 and 2016, with at least 10 human adult participants enrolled. Twenty-seven articles met the eligibility criteria. All studies investigated tumors of the anterior visual pathway. Both time-domain and spectral-domain OCT technologies were used and the role of OCT as diagnostic and/or prognostic tool was studied. Retinal OCT provides structural information about ganglion cell axon integrity and is complementary to visual function examination. OCT is a prognostic factor for post-operative visual outcome.
Topics: Humans; Nerve Compression Syndromes; Occipital Lobe; Optic Chiasm; Optic Nerve Neoplasms; Postoperative Complications; Retina; Retinal Ganglion Cells; Tomography, Optical Coherence; Visual Cortex; Visual Pathways
PubMed: 27465394
DOI: 10.1007/s10143-016-0772-1