-
Multiple Sclerosis and Related Disorders Oct 2017Visual symptoms are a common clinical manifestation of multiple sclerosis (MS) and are frequently due to acute optic neuritis (ON). However, the entire visual pathway...
Visual symptoms are a common clinical manifestation of multiple sclerosis (MS) and are frequently due to acute optic neuritis (ON). However, the entire visual pathway can be involved throughout the disease course. We describe the case of a young MS patient who experienced visual symptoms that were eventually found to be caused by retinal periphlebitis, an inflammatory process of the anterior visual pathway, which is common during MS, but rarely symptomatic. This case reinforces the concept that in all MS patients complaining visual symptoms, a complete work-up should be performed in order to rule out possible ON mimicries.
Topics: Adult; Eye; Female; Humans; Multiple Sclerosis, Relapsing-Remitting; Phlebitis; Vision Disorders; Visual Pathways
PubMed: 29055460
DOI: 10.1016/j.msard.2017.08.008 -
European Journal of Morphology Oct 1997Of the two visual systems in vertebrates, the tectofugal pathway has often been attributed to stimulus localization, while the thalamofugal pathway was thought to be... (Review)
Review
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.
Topics: Animals; Birds; Functional Laterality; Superior Colliculi; Visual Pathways
PubMed: 9290933
DOI: 10.1076/ejom.35.4.246.13080 -
Cortex; a Journal Devoted To the Study... Jul 2023Researchers have identified category-specific brain regions, such as the fusiform face area (FFA) and parahippocampal place area (PPA) in the ventral visual pathway,...
Researchers have identified category-specific brain regions, such as the fusiform face area (FFA) and parahippocampal place area (PPA) in the ventral visual pathway, which respond preferentially to one particular category of visual objects. In addition to their category-specific role in visual object identification and categorization, regions in the ventral visual pathway play critical roles in recognition memory. Nevertheless, it is not clear whether the contributions of those brain regions to recognition memory are category-specific or category-general. To address this question, the present study adopted a subsequent memory paradigm and multivariate pattern analysis (MVPA) to explore category-specific and category-general neural codes of recognition memory in the visual pathway. The results revealed that the right FFA and the bilateral PPA showed category-specific neural patterns supporting recognition memory of faces and scenes, respectively. In contrast, the lateral occipital cortex seemed to carry category-general neural codes of recognition memory. These results provide neuroimaging evidence for category-specific and category-general neural mechanisms of recognition memory in the ventral visual pathway.
Topics: Humans; Pattern Recognition, Visual; Visual Pathways; Occipital Lobe; Recognition, Psychology; Brain; Magnetic Resonance Imaging; Brain Mapping; Photic Stimulation
PubMed: 37207411
DOI: 10.1016/j.cortex.2023.04.004 -
Progress in Retinal and Eye Research Jul 2001The pattern electroretinogram (PERG) provides an objective measure of central retinal function, and has become an important element of the author's clinical visual... (Review)
Review
The pattern electroretinogram (PERG) provides an objective measure of central retinal function, and has become an important element of the author's clinical visual electrophysiological practice. The PERG contains two main components, a positivity at approximately 50ms (P50) and a larger negativity at approximately 95ms (N95). The P50 component is affected by macular dysfunction with concomitant reduction in N95. The PERG therefore complements the Ganzfeld ERG in the assessment of patients with retinal disease. In contrast, the ganglion cell origins of the N95 component allow electrophysiological evaluation of ganglion cell function both in primary disease and in dysfunction secondary to optic nerve disease, where selective loss of N95 can be observed. Both macular dysfunction and optic nerve disease can give abnormalities in the visual evoked cortical potential (VEP), and the PERG thus facilitates more meaningful VEP interpretation. This review addresses the origins and recording of the PERG, and then draws on extensive clinical data from patients with genetically determined retinal and macular dystrophies, other retinal diseases and a variety of optic nerve disorders, to present an integrated approach to diagnosis.
Topics: Electroretinography; Humans; Optic Nerve Diseases; Pattern Recognition, Visual; Retinal Degeneration; Vision Disorders; Visual Pathways
PubMed: 11390258
DOI: 10.1016/s1350-9462(00)00030-6 -
Journal of Neuro-ophthalmology : the... Mar 2002
Topics: Brain Neoplasms; Diagnosis, Differential; Humans; Optic Chiasm; Photophobia; Visual Pathways
PubMed: 11937896
DOI: 10.1097/00041327-200203000-00001 -
Academic Radiology Mar 2022Neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). We assessed the white matter microstructural integrity of the visual pathway in...
RATIONALE AND OBJECTIVES
Neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). We assessed the white matter microstructural integrity of the visual pathway in diabetes patients vs. healthy subjects, and investigated the advantages of generalized Q-sampling imaging (GQI) in the assessment of the visual pathway.
MATERIALS AND METHODS
T1-weighted, T2-weighted fluid-attenuated inversion recovery, and simultaneous multislice- diffusion sequences were acquired from 21 DR patients, 29 diabetes patients without DR (NDR group), and 28 age- and gender-matched healthy controls. Diffusion source images were reconstructed to GQI. Region of interest (ROI)-based analysis was utilized to evaluate microstructural alterations in the visual pathway. Multivariate linear regression analysis (forward stepwise method) was performed to investigate associations between clinical data and mean GQI parameters.
RESULTS
ROI-based analyses indicated that the GQI parameters generalized fractional anisotropy, quantitative anisotropy (QA), and normalized QA (NQA) were significantly lower in the NDR group than in the healthy controls, and even lower in the DR group than in the NDR group. Disease duration was significantly and negatively correlated with mean generalized fractional anisotropy and mean NQA.
CONCLUSION
GQI could sensitively and non-invasively evaluate the visual pathway in diabetes patients. The nerve fibers of the visual pathway were damaged before the onset of retinopathy, and this damage was aggravated after retinopathy onset, as a consequence of long exposure to hyperglycemia.
Topics: Anisotropy; Brain; Diabetes Mellitus, Type 2; Diffusion Tensor Imaging; Humans; Retinal Diseases; Visual Pathways; White Matter
PubMed: 34930656
DOI: 10.1016/j.acra.2021.10.021 -
NeuroImage May 2022Despite decades of research, our understanding of the relationship between color and form processing in the primate ventral visual pathway remains incomplete. Using fMRI...
Despite decades of research, our understanding of the relationship between color and form processing in the primate ventral visual pathway remains incomplete. Using fMRI multivoxel pattern analysis, we examined coding of color and form, using a simple form feature (orientation) and a mid-level form feature (curvature), in human ventral visual processing regions. We found that both color and form could be decoded from activity in early visual areas V1 to V4, as well as in the posterior color-selective region and shape-selective regions in ventral and lateral occipitotemporal cortex defined based on their univariate selectivity to color or shape, respectively (the central color region only showed color but not form decoding). Meanwhile, decoding biases towards one feature or the other existed in the color- and shape-selective regions, consistent with their univariate feature selectivity reported in past studies. Additional extensive analyses show that while all these regions contain independent (linearly additive) coding for both features, several early visual regions also encode the conjunction of color and the simple, but not the complex, form feature in a nonlinear, interactive manner. Taken together, the results show that color and form are encoded in a biased distributed and largely independent manner across ventral visual regions in the human brain.
Topics: Animals; Brain Mapping; Humans; Magnetic Resonance Imaging; Pattern Recognition, Visual; Photic Stimulation; Visual Cortex; Visual Pathways
PubMed: 35122966
DOI: 10.1016/j.neuroimage.2022.118941 -
Emergency Medicine Clinics of North... Feb 2008Neuro-ophthalmologic disorders arise from all areas of the neuro-ophthalmologic tract. They may be expressed simply as loss of vision or double vision, or as complex... (Review)
Review
Neuro-ophthalmologic disorders arise from all areas of the neuro-ophthalmologic tract. They may be expressed simply as loss of vision or double vision, or as complex syndromes or systemic illnesses, depending on the location and type of lesion. Problems may occur anywhere along the visual pathway, including the brainstem, cavernous sinus, subarachnoid space, and orbital apex, and may affect adjacent structures also. A firm understanding of the neuroanatomy and neurophysiology of the eye is essential to correct diagnosis.
Topics: Cranial Nerve Diseases; Cranial Nerves; Diagnostic Techniques, Ophthalmological; Diplopia; Eye Movements; Horner Syndrome; Humans; Optic Nerve; Visual Pathways
PubMed: 18249261
DOI: 10.1016/j.emc.2007.11.004 -
Cell Reports Oct 2018In the primate visual system, direction-selective (DS) neurons are critical for visual motion perception. While DS neurons in the dorsal visual pathway have been well...
In the primate visual system, direction-selective (DS) neurons are critical for visual motion perception. While DS neurons in the dorsal visual pathway have been well characterized, the response properties of DS neurons in other major visual areas are largely unexplored. Recent optical imaging studies in monkey visual cortex area 2 (V2) revealed clusters of DS neurons. This imaging method facilitates targeted recordings from these neurons. Using optical imaging and single-cell recording, we characterized detailed response properties of DS neurons in macaque V2. Compared with DS neurons in the dorsal areas (e.g., middle temporal area [MT]), V2 DS neurons have a smaller receptive field and a stronger antagonistic surround. They do not code speed or plaid motion but are sensitive to motion contrast. Our results suggest that V2 DS neurons play an important role in figure-ground segregation. The clusters of V2 DS neurons are likely specialized functional systems for detecting motion contrast.
Topics: Animals; Macaca fascicularis; Motion Perception; Visual Pathways; Visual Perception
PubMed: 30282025
DOI: 10.1016/j.celrep.2018.09.014 -
Cerebral Cortex (New York, N.Y. : 1991) Jan 2003How does the cortical circuitry analyze the visual scene? Here we explore the earliest levels of striate cortical processing: the first stage, where orientation... (Review)
Review
How does the cortical circuitry analyze the visual scene? Here we explore the earliest levels of striate cortical processing: the first stage, where orientation sensitivity emerges, and the second stage, where stimulus selectivity is further refined. The approach is whole cell recording from cat in vivo. Neurons in the lateral geniculate nucleus of the thalamus have circular receptive fields whose subregions, center and surround are concentrically arranged and have the reverse sign, on or off. These neurons supply cortical simple cells, whose receptive fields have on and off subregions that are elongated and lie side by side. Feedforward models hold that orientation sensitivity depends on this thalamocortical change in receptive field structure and an arrangement within subregions such that stimuli of the reverse contrast evoke synaptic responses of the opposite polarity-push-pull. Our work provides support for feedforward models and emphasizes that push-pull is key in the geniculostriate pathway, preserved from retina by thalamic relay cells and reiterated, point by point, by cortical simple cells. Also, we help define the cortical push-pull circuit by identifying inhibitory simple cells. Lastly, separate experiments that compare the first and second levels of cortical processing suggest that differences in the synaptic physiology of connections at the two (thalamocortical versus intracortical) stages underlie differential selectivity for properties such as motion.
Topics: Animals; Cats; Models, Neurological; Nerve Net; Neural Inhibition; Thalamus; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 12466216
DOI: 10.1093/cercor/13.1.63