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Current Opinion in Neurobiology Dec 2018Vision is the sense humans rely on most to navigate the world and survive. A tremendous amount of research has focused on understanding the neural circuits for vision... (Review)
Review
Vision is the sense humans rely on most to navigate the world and survive. A tremendous amount of research has focused on understanding the neural circuits for vision and the developmental mechanisms that establish them. The eye-to-brain, or 'retinofugal' pathway remains a particularly important model in these contexts because it is essential for sight, its overt anatomical features relate to distinct functional attributes and those features develop in a tractable sequence. Much progress has been made in understanding the growth of retinal axons out of the eye, their selection of targets in the brain, the development of laminar and cell type-specific connectivity within those targets, and also dendritic connectivity within the retina itself. Moreover, because the retinofugal pathway is prone to degeneration in many common blinding diseases, understanding the cellular and molecular mechanisms that establish connectivity early in life stands to provide valuable insights into approaches that re-wire this pathway after damage or loss. Here we review recent progress in understanding the development of retinofugal pathways and how this information is important for improving visual circuit regeneration.
Topics: Animals; Axons; Humans; Nerve Regeneration; Optic Nerve; Optic Tract; Retinal Ganglion Cells; Visual Pathways
PubMed: 30339988
DOI: 10.1016/j.conb.2018.10.001 -
Current Opinion in Neurology Jun 2019Multiple sclerosis (MS) and related autoimmune disorders of the central nervous system such as neuromyelitis optica spectrum disorders (NMOSD) are characterized by... (Review)
Review
PURPOSE OF REVIEW
Multiple sclerosis (MS) and related autoimmune disorders of the central nervous system such as neuromyelitis optica spectrum disorders (NMOSD) are characterized by chronic disability resulting from autoimmune neuroinflammation, with demyelination, astrocyte damage, impaired axonal transmission and neuroaxonal loss. Novel therapeutics stopping or reversing the progression of disability are still urgently warranted. This review addresses research on optic neuritis in preclinical experimental models and their translation to clinical trials.
RECENT FINDINGS
Optic neuritis can be used as paradigm for an MS relapse which can serve to evaluate the efficacy of novel therapeutics in clinical trials with a reasonable duration and cohort size. The advantage is the linear structure of the visual pathway allowing the assessment of visual function and retinal structure as highly sensitive outcome parameters. Experimental autoimmune encephalomyelitis is an inducible, inflammatory and demyelinating central nervous system disease extensively used as animal model of MS. Optic neuritis is part of the clinicopathological manifestations in a number of experimental autoimmune encephalomyelitis models. These have gained increasing interest for studies evaluating neuroprotective and/or remyelinating substances as longitudinal, visual and retinal readouts have become available.
SUMMARY
Translation of preclinical experiments, evaluating neuroprotective or remyelinating therapeutics to clinical studies is challenging. In-vivo readouts like optical coherence tomography, offers the possibility to transfer experimental study designs to clinical optic neuritis trials.
Topics: Animals; Axons; Encephalomyelitis, Autoimmune, Experimental; Humans; Multiple Sclerosis; Optic Neuritis; Retina; Tomography, Optical Coherence; Visual Pathways
PubMed: 30694926
DOI: 10.1097/WCO.0000000000000675 -
Ultrasound in Obstetrics & Gynecology :... Oct 2023
Topics: Humans; Visual Pathways; Diffusion Tensor Imaging; Neurosurgical Procedures
PubMed: 37218109
DOI: 10.1002/uog.26269 -
Brain and Behavior Dec 2019Multiple sclerosis (MS) is a heterogeneous disease with an unpredictable course. Visual pathway is a target of the disease and may reflect mechanisms that lead to...
INTRODUCTION
Multiple sclerosis (MS) is a heterogeneous disease with an unpredictable course. Visual pathway is a target of the disease and may reflect mechanisms that lead to disability. Structural and functional changes in the visual pathway may be studied by noninvasive techniques such as optical coherence tomography (OCT), visual evoked potentials (VEP), or B-mode transorbital sonography (TOS).
OBJECTIVES
The aim is to assess changes in the visual pathway in eyes of MS patients with and without a history of optic neuritis over a 3-year period and to explore their relationship with disability.
MATERIALS AND METHODS
In total, 112 eyes from 56 patients with relapsing MS were recruited: 29 with, and 83 without a history of ON (hON and nhON, respectively). Several parameters were measured by OCT, VEP, and TOS. Baseline measurements were also compared to 29 healthy controls. At 36 months, measurements were repeated in all eyes.
RESULTS
At baseline, all tests showed significant differences in optic nerve structure and function in both patient cohorts in all the parameters studied, suggestive of more impairment of the visual pathway among the hON cohort. OCT showed significant differences between healthy controls and the nhON cohort. At 36 months, the nhON cohort showed significant changes by OCT, VEP, and TOS suggestive of further visual pathway impairment. OCT measurements also correlated with baseline EDSS among the nhON cohort.
CONCLUSIONS
OCT is the most suitable technique and outperforms VEP and TOS to detect subclinical damage in the visual pathway. It discriminated MS patients from healthy controls and showed a progressive decline in optic nerve thickness over time among these patients.
Topics: Adult; Disability Evaluation; Disease Progression; Evoked Potentials, Visual; Female; Humans; Male; Middle Aged; Multiple Sclerosis; Optic Nerve; Tomography, Optical Coherence; Ultrasonography; Visual Pathways
PubMed: 31733096
DOI: 10.1002/brb3.1467 -
Brain : a Journal of Neurology Jan 2015Visual impairment is a key manifestation of multiple sclerosis. Acute optic neuritis is a common, often presenting manifestation, but visual deficits and structural loss... (Review)
Review
Visual impairment is a key manifestation of multiple sclerosis. Acute optic neuritis is a common, often presenting manifestation, but visual deficits and structural loss of retinal axonal and neuronal integrity can occur even without a history of optic neuritis. Interest in vision in multiple sclerosis is growing, partially in response to the development of sensitive visual function tests, structural markers such as optical coherence tomography and magnetic resonance imaging, and quality of life measures that give clinical meaning to the structure-function correlations that are unique to the afferent visual pathway. Abnormal eye movements also are common in multiple sclerosis, but quantitative assessment methods that can be applied in practice and clinical trials are not readily available. We summarize here a comprehensive literature search and the discussion at a recent international meeting of investigators involved in the development and study of visual outcomes in multiple sclerosis, which had, as its overriding goals, to review the state of the field and identify areas for future research. We review data and principles to help us understand the importance of vision as a model for outcomes assessment in clinical practice and therapeutic trials in multiple sclerosis.
Topics: Animals; Databases, Factual; Eye Diseases; Humans; Multiple Sclerosis; Vision, Ocular; Visual Pathways
PubMed: 25433914
DOI: 10.1093/brain/awu335 -
Journal of Neuro-ophthalmology : the... Sep 2022Perimetry is widely used in the localization of retrochiasmal visual pathway lesions. Although macular sparing, homonymous paracentral scotomas, and quadrantanopias are...
BACKGROUND
Perimetry is widely used in the localization of retrochiasmal visual pathway lesions. Although macular sparing, homonymous paracentral scotomas, and quadrantanopias are regarded as features of posterior retrochiasmal visual pathway lesions, incongruous hemianopia is regarded as a hallmark of anterior lesions. Recent studies have questioned the specificity of these defect patterns.
METHODS
Retrospective record review conducted in a single, academic, medical center using an electronic search engine with the terms ""homonymous hemianopia," "optic tract," "temporal lobectomy," "visual field defect," and "MRI." Patients were included if they had reliable, automated, static visual fields, high-quality reviewable MRI scans, and pertinent lesions. MRI lesions were assigned to 1 of 6 retrochiasmal visual pathway segments by the study neuroradiologist. Two study authors independently reviewed the visual fields and designated 10 different defect patterns.
RESULTS
From an original cohort of 256 cases, only 83 had MRI-defined lesions that were limited to particular retrochiasmal segments and had visual field defect patterns that allegedly permitted localization to those particular segments. The 5 contralateral nerve fiber bundle defects were exclusive to optic tract tumors with rostral extension. Pie-in-the-sky defects were exclusive to Meyer loop lesions. Among 22 fields with macular sparing, 86% arose from the visual cortex or posterior optic radiations. Among 31 fields with homonymous quadrantanopias, 77% arose from Meyer loop, visual cortex, or posterior optic radiations. Among 13 fields with homonymous paracentral scotomas, 69% arose from visual cortex or posterior optic radiations. Optic tract lesions accounted for 70% of incongruous hemianopias but that pattern occurred uncommonly.
CONCLUSION
In correlating discrete MRI-defined retrochiasmal lesions with visual field defect patterns identified on static perimetry, this study showed that macular sparing, homonymous paracentral scotomas, and quadrantanopias localized to the visual cortex and posterior optic radiations segments but not exclusively. It has differed from an earlier study in showing that incongruous hemianopias occur predominantly from optic tract lesions.
Topics: Hemianopsia; Humans; Retrospective Studies; Scotoma; Vision Disorders; Visual Field Tests; Visual Fields; Visual Pathways
PubMed: 36166759
DOI: 10.1097/WNO.0000000000001601 -
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 -
Nature Neuroscience Oct 2017Distinct processing of objects and space has been an organizing principle for studying higher-level vision and medial temporal lobe memory. Here, however, we discuss how... (Review)
Review
Distinct processing of objects and space has been an organizing principle for studying higher-level vision and medial temporal lobe memory. Here, however, we discuss how object and spatial information are in fact closely integrated in vision and memory. The ventral, object-processing visual pathway carries precise spatial information, transformed from retinotopic coordinates into relative dimensions. At the final stages of the ventral pathway, including the dorsal anterior temporal lobe (TEd), object-sensitive neurons are intermixed with neurons that process large-scale environmental space. TEd projects primarily to perirhinal cortex (PRC), which in turn projects to lateral entorhinal cortex (LEC). PRC and LEC also combine object and spatial information. For example, PRC and LEC neurons exhibit place fields that are evoked by landmark objects or the remembered locations of objects. Thus, spatial information, on both local and global scales, is deeply integrated into the ventral (temporal) object-processing pathway in vision and memory.
Topics: Animals; Humans; Memory; Pattern Recognition, Visual; Photic Stimulation; Space Perception; Vision, Ocular; Visual Pathways
PubMed: 29073645
DOI: 10.1038/nn.4657 -
Journal of Neuro-ophthalmology : the... Jun 2023Anti-NMDA receptor (NMDAR) encephalitis patients have been reported to exhibit visual dysfunction without retinal thinning. The objective of our study was to examine the...
BACKGROUND
Anti-NMDA receptor (NMDAR) encephalitis patients have been reported to exhibit visual dysfunction without retinal thinning. The objective of our study was to examine the involvement of the visual pathway structure and function in anti-NMDAR encephalitis by assessing postrecovery visual function and retinal structure, and acute-phase occipital cortex function.
METHODS
In this cross-sectional study, patients diagnosed with anti-NMDAR encephalitis per consensus criteria underwent postrecovery visual acuity (VA) testing and optical coherence tomography (OCT) with automated retinal layer segmentation. Clinical data and acute-phase brain 18F-fluorodeoxyglucose (FDG) PET/CT (performed within 90 days of symptom onset, assessed qualitatively and semi-quantitatively) were retrospectively analyzed. VA and OCT measures were compared between anti-NMDAR and age, sex, and race-matched healthy controls (HC). When available, FDG-PET/CT metabolism patterns were analyzed for correlations with VA, and OCT measures.
RESULTS
A total of 16 anti-NMDAR (32 eyes) and 32 HC (64 eyes) were included in the study. Anti-NMDAR exhibited lower low-contrast VA (2.5% contrast: -4.4 letters [95% CI; -8.5 to -0.3]; P = 0.04, 1.25% contrast: -6.8 letters [95%CI; -12 to -1.7]; P = 0.01) compared with HC, but no differences were found on OCT-derived retinal layer thicknesses. Acute-phase FDG-PET/CT medial occipital cortex metabolism did not correlate with follow-up low-contrast VA or ganglion cell/inner plexiform layer thickness (GCIPL) (n = 7, 2.5% contrast: r = -0.31; P = 0.50, 1.25% contrast: r = -0.34; P = 0.45, GCIPL: r = -0.04; P = 0.94).
CONCLUSIONS
Although the visual system seems to be involved in anti-NMDAR encephalitis, no retinal structural or occipital cortex functional abnormalities seem to be responsible for the visual dysfunction. When detected acutely, occipital lobe hypometabolism in anti-NMDAR encephalitis does not seem to associate with subsequent retrograde trans-synaptic degenerative phenomena, potentially reflecting reversible neuronal/synaptic dysfunction in the acute phase of the illness rather than neuronal degeneration.
Topics: Humans; Retinal Ganglion Cells; Fluorodeoxyglucose F18; Positron Emission Tomography Computed Tomography; Tomography, Optical Coherence; Anti-N-Methyl-D-Aspartate Receptor Encephalitis; Retrospective Studies; Visual Pathways; Cross-Sectional Studies; Nerve Fibers; Visual Acuity
PubMed: 36000788
DOI: 10.1097/WNO.0000000000001696 -
Zhurnal Voprosy Neirokhirurgii Imeni N.... 2021Optical coherence tomography (OCT) gives the opportunity to examine retrograde degeneration of visual pathway damaged at various levels.
BACKGROUND
Optical coherence tomography (OCT) gives the opportunity to examine retrograde degeneration of visual pathway damaged at various levels.
OBJECTIVE
To estimate OCT data on retrograde degeneration of visual pathway damaged at various levels.
MATERIAL AND METHODS
Ganglion cell layer (GCL) thickness was measured by OCT in 79 patients with visual pathway damaged at various levels and known duration of visual disturbances. Twenty-One patients were diagnosed with traumatic lesions of the optic nerves and/or chiasma. Fifty-eight patients had retro-genicular visual pathway damage. Thirty-three patients were examined for postoperative homonymous hemianopia after surgery for drug-resistant temporal lobe epilepsy. Twenty-five patients were diagnosed with occipital lobe damage following stroke (12 patients), surgery for arteriovenous malformation (11 patients) and traumatic brain injury (2 patients). All patients underwent assessment of visual acuity, automatic static perimetry, MRI/CT of the brain. Retinal ganglion cell complex was analyzed during OCT.
RESULTS
GCL thinning following anterior visual pathway damage was detected in 20 out of 21 patients after ≥22 days. In case of post-genicular visual pathway damage, GCL thinning was found in 25 out of 58 patients (9 out of 33 ones after surgery for temporal lobe epilepsy and 16 out of 25 patients with occipital lobe lesion). After surgery for temporal lobe epilepsy, minimum period until GCL thinning detection after previous visual pathway damage was 3 months, in case of occipital lobe lesion - 5 months.
CONCLUSION
Retrograde visual pathway degeneration is followed by GCL thinning and depends on the level of visual pathway lesion.
Topics: Humans; Occipital Lobe; Retinal Ganglion Cells; Retrograde Degeneration; Tomography, Optical Coherence; Visual Pathways
PubMed: 34951765
DOI: 10.17116/neiro20218506192