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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 -
The Journal of Comparative Neurology Dec 2020Visual perception requires both visual information and attention. This review compares, across classes of vertebrates, the functional and anatomical characteristics of... (Review)
Review
Visual perception requires both visual information and attention. This review compares, across classes of vertebrates, the functional and anatomical characteristics of (a) the neural pathways that process visual information about objects, and (b) stimulus selection pathways that determine the objects to which an animal attends. Early in the evolution of vertebrate species, visual perception was dominated by information transmitted via the midbrain (retinotectal) visual pathway, and attention was probably controlled primarily by a selection network in the midbrain. In contrast, in primates, visual perception is dominated by information transmitted via the forebrain (retinogeniculate) visual pathway, and attention is mediated largely by networks in the forebrain. In birds and nonprimate mammals, both the retinotectal and retinogeniculate pathways contribute critically to visual information processing, and both midbrain and forebrain networks play important roles in controlling attention. The computations and processing strategies in birds and mammals share some strikingly similar characteristics despite over 300 million years of independent evolution and being implemented by distinct brain architectures. The similarity of these functional characteristics suggests that they provide valuable advantages to visual perception in advanced visual systems. A schema is proposed that describes the evolution of the pathways and computations that enable visual perception in vertebrate species.
Topics: Animals; Biological Evolution; Birds; Brain; Humans; Mammals; Nerve Net; Retina; Retinal Neurons; Superior Colliculi; Vertebrates; Visual Pathways; Visual Perception
PubMed: 32003466
DOI: 10.1002/cne.24871 -
Journal of Vision Aug 2020The crowding effect, defined as the detrimental effects of nearby items on visual object recognition, has been extensively investigated. Previous studies have primarily...
The crowding effect, defined as the detrimental effects of nearby items on visual object recognition, has been extensively investigated. Previous studies have primarily focused on finding the stage(s) in the visual hierarchy where crowding starts to limit target processing, while little attention has been focused on potential differences between the parvocellular (P) and magnocellular (M) pathways in crowding mechanisms. Here, we investigated the crowding effect in these parallel visual pathways. In Experiment 1, stimuli were designed to separately engage the P or M pathway, by tuning stimulus and background features (e.g., temporal frequency and color) to activate the targeted pathway and saturate the other pathway, respectively. Results showed that at the same eccentricity and with the same tasks, targets processed in the M pathway appeared to be more vulnerable to crowding effect. In Experiment 2, crowding effects were studied using three different types of stimuli and visual tasks (form, color, and motion), presumably with different degrees of dependence on the P and M pathways. Results revealed that color, motion, and form discrimination were increasingly more affected by crowding. We conclude that processing in the M and P pathways are differentially impacted by crowding; and importantly, crowding seems to affect processing of spatial forms more than other stimulus properties.
Topics: Adolescent; Adult; Attention; Color; Color Perception; Crowding; Female; Form Perception; Humans; Male; Motion Perception; Pattern Recognition, Visual; Photic Stimulation; Visual Pathways; Young Adult
PubMed: 32749447
DOI: 10.1167/jov.20.8.6 -
Graefe's Archive For Clinical and... Jun 2023To investigate the impact of Boston Type I Keratoprosthesis (BI-Kpro) implantation on retinal and visual pathway function, respectively, assessed by full-field...
PURPOSE
To investigate the impact of Boston Type I Keratoprosthesis (BI-Kpro) implantation on retinal and visual pathway function, respectively, assessed by full-field electroretinography (ERG) and visually evoked potentials (VEPs).
METHODS
This is a prospective interventional longitudinal study, and patients with BI-Kpro implantation were assessed preoperatively and at 3 and 12 months after surgery. ERG, flash, and pattern-reversal VEPs (15' and 60' checks) along with visual acuity (VA) were performed.
RESULTS
A total of 13 patients (24 to 88 years of age) were included. Mean baseline VA (logMAR) improved from 2.30 to 1.04 at 3 months and to 1.00 at 12 months. Flash VEPs were normal in 6 (46%) patients and in 10 (77%) patients at the 12-month follow-up. PVEP was non-detectable in all patients preoperatively for both check sizes. For 15' check size, 6 (46%) patients showed responses after 3 and 12 months except for 1 patient with normal responses at 12 months with the remaining non-detectable. For 60' checks, 11 (85%) patients had responses 3 months after surgery with only 9 (70%) showing responses at 12 months. Abnormal full-field ERGs were found in all patients preoperatively. Amplitude improvement was found in 10 (77%) patients from baseline to 3 months and in 8 (62%) patients from the 3- to the 12-month follow-up.
CONCLUSIONS
In this small cohort of patients with BI-Kpro implantation, a remarkable improvement on visual function quantitatively assessed by electrophysiological testing was found in the majority of cases. Visual electrophysiological testing can contribute to objectively assess functional outcomes in this population.
Topics: Humans; Cornea; Visual Pathways; Prospective Studies; Longitudinal Studies; Prostheses and Implants; Corneal Diseases; Evoked Potentials, Visual
PubMed: 36633667
DOI: 10.1007/s00417-022-05961-7 -
Journal of Comparative Physiology. A,... Mar 2020
Topics: Animals; Arthropods; Brain; Drosophila melanogaster; Feedback, Sensory; Vision, Ocular; Visual Pathways; Visual Perception
PubMed: 32036403
DOI: 10.1007/s00359-020-01407-9 -
Neuroscience Bulletin Oct 2021Visual object recognition in humans and nonhuman primates is achieved by the ventral visual pathway (ventral occipital-temporal cortex, VOTC), which shows a...
Visual object recognition in humans and nonhuman primates is achieved by the ventral visual pathway (ventral occipital-temporal cortex, VOTC), which shows a well-documented object domain structure. An on-going question is what type of information is processed in the higher-order VOTC that underlies such observations, with recent evidence suggesting effects of certain visual features. Combining computational vision models, fMRI experiment using a parametric-modulation approach, and natural image statistics of common objects, we depicted the neural distribution of a comprehensive set of visual features in the VOTC, identifying voxel sensitivities with specific feature sets across geometry/shape, Fourier power, and color. The visual feature combination pattern in the VOTC is significantly explained by their relationships to different types of response-action computation (fight-or-flight, navigation, and manipulation), as derived from behavioral ratings and natural image statistics. These results offer a comprehensive visual feature map in the VOTC and a plausible theoretical explanation as a mapping onto different types of downstream response-action systems.
Topics: Animals; Brain Mapping; Humans; Magnetic Resonance Imaging; Occipital Lobe; Pattern Recognition, Visual; Photic Stimulation; Temporal Lobe; Visual Pathways; Visual Perception
PubMed: 34215969
DOI: 10.1007/s12264-021-00734-4 -
Neuroscience Aug 2021Some patients with damage to the primary visual cortex (V1) exhibit visuomotor ability, despite loss of visual awareness, a phenomenon termed "blindsight". We review a... (Review)
Review
Some patients with damage to the primary visual cortex (V1) exhibit visuomotor ability, despite loss of visual awareness, a phenomenon termed "blindsight". We review a series of studies conducted mainly in our laboratory on macaque monkeys with unilateral V1 lesioning to reveal the neural pathways underlying visuomotor transformation and the cognitive capabilities retained in blindsight. After lesioning, it takes several weeks for the recovery of visually guided saccades toward the lesion-affected visual field. In addition to the lateral geniculate nucleus, the pathway from the superior colliculus to the pulvinar participates in visuomotor processing in blindsight. At the cortical level, bilateral lateral intraparietal regions become critically involved in the saccade control. These results suggest that the visual circuits experience drastic changes while the monkey acquires blindsight. In these animals, analysis based on signal detection theory adapted to behavior in the "Yes-No" task indicates reduced sensitivity to visual targets, suggesting that visual awareness is impaired. Saccades become less accurate, decisions become less deliberate, and some forms of bottom-up attention are impaired. However, a variety of cognitive functions are retained such as saliency detection during free viewing, top-down attention, short-term spatial memory, and associative learning. These observations indicate that blindsight is not a low-level sensory-motor response, but the residual visual inputs can access these cognitive capabilities. Based on these results we suggest that the macaque model of blindsight replicates type II blindsight patients who experience some "feeling" of objects, which guides cognitive capabilities that we naïvely think are not possible without phenomenal consciousness.
Topics: Animals; Geniculate Bodies; Humans; Macaca; Photic Stimulation; Saccades; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 34153356
DOI: 10.1016/j.neuroscience.2021.06.022 -
Trends in Cognitive Sciences Dec 2022A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance.... (Review)
Review
A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance. Such 'global' shape representations are achieved by describing objects via the spatial arrangement of their local features, or structure, rather than by the appearance of the features themselves. However, accumulating evidence suggests that the ventral visual pathway - the primary substrate underlying object recognition - may not represent global shape. Instead, ventral representations may be better described as a basis set of local image features. We suggest that this evidence forces a reevaluation of the role of the ventral pathway in object perception and posits a broader network for shape perception that encompasses contributions from the dorsal pathway.
Topics: Humans; Visual Pathways; Pattern Recognition, Visual; Visual Perception; Brain; Magnetic Resonance Imaging
PubMed: 36272937
DOI: 10.1016/j.tics.2022.09.019 -
Molecular Neurobiology Jul 2021Visual disabilities in central nervous system autoimmune diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE),... (Review)
Review
Visual disabilities in central nervous system autoimmune diseases such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are important symptoms. Past studies have focused on neuro-inflammatory changes and demyelination in the white matter of the brain and spinal cord. In MS, neuro-inflammatory lesions have been diagnosed in the visual pathway; the lesions may perturb visual function. Similarly, neuropathological changes in the retina and optic nerves have been found in animals with chronic EAE. Although the retina and optic nerves are immunologically privileged sites via the blood-retina barrier and blood-brain barrier, respectively, inflammation can occur via other routes, such as the uvea (e.g., iris and choroid) and cerebrospinal fluid in the meninges. This review primarily addresses the direct involvement of the blood-retina barrier and the blood-brain barrier in the development of retinitis and optic neuritis in EAE models. Additional routes, including pro-inflammatory mediator-filled choroidal and subarachnoid spaces, are also discussed with respect to their roles in EAE-induced visual disability and as analogues of MS in humans.
Topics: Animals; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Humans; Multiple Sclerosis; Optic Neuritis; Uveitis; Vision Disorders; Visual Pathways
PubMed: 33745114
DOI: 10.1007/s12035-021-02355-4 -
Trends in Cognitive Sciences Jul 2021
Topics: Cognition; Humans; Motion Perception; Visual Cortex; Visual Pathways
PubMed: 34024730
DOI: 10.1016/j.tics.2021.04.002