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Vision Research Aug 2007It is well established that sensitivity is not necessarily equivalent at isoeccentric locations across the visual field. The focus of this study was a psychophysical...
It is well established that sensitivity is not necessarily equivalent at isoeccentric locations across the visual field. The focus of this study was a psychophysical examination of the spatial sensitivity differences between the upper and lower visual hemifields under conditions biased toward the presumed magnocellular or parvocellular visual pathway. Experiment 1 showed higher contrast sensitivity in the lower visual field when visual sensitivity was biased toward the parvocellular pathway; no visual field anisotropy was found when sensitivity was biased toward the magnocellular pathway. Experiment 2 showed that the magnitude of the contrast sensitivity anisotropy within the presumed parvocellular pathway increased when test targets of higher spatial frequency were used. The results of this study have relevance for the design both of psychophysical paradigms and clinical training programs for patients with heterogeneous visual field loss.
Topics: Adult; Anisotropy; Contrast Sensitivity; Female; Humans; Male; Middle Aged; Photic Stimulation; Psychophysics; Sensory Thresholds; Visual Fields; Visual Pathways
PubMed: 17662333
DOI: 10.1016/j.visres.2007.05.013 -
The Journal of Physiology Jun 2009The first paper of Hubel and Wiesel in The Journal of Physiology in 1959 marked the beginning of an exciting chapter in the history of visual neuroscience. Through a... (Review)
Review
The first paper of Hubel and Wiesel in The Journal of Physiology in 1959 marked the beginning of an exciting chapter in the history of visual neuroscience. Through a collaboration that lasted 25 years, Hubel and Wiesel described the main response properties of visual cortical neurons, the functional architecture of visual cortex and the role of visual experience in shaping cortical architecture. The work of Hubel and Wiesel transformed the field not only through scientific discovery but also by touching the life and scientific careers of many students. Here, I describe my personal experience as a postdoctoral student with Torsten Wiesel and how this experience influenced my own work.
Topics: Animals; Geniculate Bodies; History, 20th Century; Humans; Neural Pathways; Neurology; Retina; Visual Cortex; Visual Pathways
PubMed: 19525563
DOI: 10.1113/jphysiol.2009.169813 -
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 -
The British Journal of Ophthalmology Sep 2006Implications for our understanding of the mechanisms of early development of the visual pathway
Implications for our understanding of the mechanisms of early development of the visual pathway
Topics: Albinism, Ocular; Fovea Centralis; Humans; Optic Chiasm; Visual Pathways
PubMed: 16929052
DOI: 10.1136/bjo.2006.097618 -
Neuroradiology Jun 2009Orbital and anterior visual pathway infection and inflammation represent approximately 10-15% of all orbital pathology. Both conditions can occur separately but... (Review)
Review
INTRODUCTION
Orbital and anterior visual pathway infection and inflammation represent approximately 10-15% of all orbital pathology. Both conditions can occur separately but occasionally they can be observed simultaneously.
METHODS
While the diagnosis of infection is usually straightforward, it is important to depict the lesions and to know the potential devastating complications. CT plays an important role in confirming the clinical suspicion of orbital infection.
RESULTS
The diagnosis and differential diagnosis of inflammation is more challenging. Differentiating inflammation from lymphoproliferative diseases and tumours can be difficult.
CONCLUSION
MR imaging plays an important role but a dedicated orbital imaging protocol is mandatory.
Topics: Eye Infections; Humans; Magnetic Resonance Imaging; Optic Nerve Diseases; Tomography, X-Ray Computed; Visual Pathways
PubMed: 19221728
DOI: 10.1007/s00234-009-0505-z -
Asian Journal of Surgery Mar 2023
Topics: Humans; Visual Pathways; Hand; Upper Extremity; Foot; Lower Extremity
PubMed: 36244904
DOI: 10.1016/j.asjsur.2022.09.061 -
Asian Journal of Surgery Mar 2023
Topics: Humans; Visual Pathways; Hand; Upper Extremity; Foot; Lower Extremity
PubMed: 36167655
DOI: 10.1016/j.asjsur.2022.09.015 -
PLoS Computational Biology Mar 2021While vision evokes a dense network of feedforward and feedback neural processes in the brain, visual processes are primarily modeled with feedforward hierarchical...
While vision evokes a dense network of feedforward and feedback neural processes in the brain, visual processes are primarily modeled with feedforward hierarchical neural networks, leaving the computational role of feedback processes poorly understood. Here, we developed a generative autoencoder neural network model and adversarially trained it on a categorically diverse data set of images. We hypothesized that the feedback processes in the ventral visual pathway can be represented by reconstruction of the visual information performed by the generative model. We compared representational similarity of the activity patterns in the proposed model with temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) visual brain responses. The proposed generative model identified two segregated neural dynamics in the visual brain. A temporal hierarchy of processes transforming low level visual information into high level semantics in the feedforward sweep, and a temporally later dynamics of inverse processes reconstructing low level visual information from a high level latent representation in the feedback sweep. Our results append to previous studies on neural feedback processes by presenting a new insight into the algorithmic function and the information carried by the feedback processes in the ventral visual pathway.
Topics: Adult; Algorithms; Brain; Computational Biology; Feedback, Physiological; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetoencephalography; Neural Networks, Computer; Visual Cortex; Visual Pathways; Young Adult
PubMed: 33760819
DOI: 10.1371/journal.pcbi.1008775 -
Multiple Sclerosis (Houndmills,... Oct 2018This study aims to investigate whether bidirectional degeneration occurs within the visual pathway and, if so, the extent of such changes in neuromyelitis optica...
OBJECTIVE
This study aims to investigate whether bidirectional degeneration occurs within the visual pathway and, if so, the extent of such changes in neuromyelitis optica spectrum disorder (NMOSD).
METHODS
In total, 36 NMOSD and 24 healthy controls (HCs) were enrolled. Three-dimensional T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging were used to analyze damage to the posterior visual pathway. Damage to the anterior visual pathway was measured by optical coherence tomography.
RESULTS
In total, 24 NMOSD with prior optic neuritis (NMOON) patients showed significant reduction of peripapillary retinal nerve fiber layer, inner and outer retinal thickness, lateral geniculate nucleus volume, primary visual cortex volume, and decreased integrity of optic radiations, compared with 12 NMOSD without prior optic neuritis (NMONON) patients and 24 HCs. In NMONON, only the inner retinal thickness and the integrity of optic radiations were significantly reduced in comparison with HCs. Moreover, patients with optic neuritis showed severe bidirectional degeneration, the loss of the RNFL was greater than the atrophy of V1.
CONCLUSION
Our study indicated the presence of trans-synaptic degeneration in NMOSD. Damage to the inner retina and optic radiations can be observed even in NMONON. After an episode of optic neuritis, the anterior visual pathway damage is greater than the posterior visual pathway damage.
Topics: Adult; Cross-Sectional Studies; Diffusion Tensor Imaging; Female; Humans; Imaging, Three-Dimensional; Male; Middle Aged; Nerve Degeneration; Neuromyelitis Optica; Tomography, Optical Coherence; Visual Cortex; Visual Pathways
PubMed: 28823217
DOI: 10.1177/1352458517727604 -
Arquivos Brasileiros de Oftalmologia 2011The pattern electroretinogram is an electrophysiological test that assesses the function of inner retinal layers, particularly the ganglion cells layer of retina, using... (Review)
Review
The pattern electroretinogram is an electrophysiological test that assesses the function of inner retinal layers, particularly the ganglion cells layer of retina, using a reversing checkerboard or grating pattern that produces no change in average luminance over time. The normal pattern electroretinogram is composed of a proeminent positive component (P50) and a large later negative component (N95). Since structural damage that compromises the retinal ganglion cell layer can lead to pattern electroretinogram changes, particularly in the N95 amplitude, the test can be useful in the treatment of a number of anterior visual pathway diseases. In this article, we review the methods for recording pattern electroretinogram and its usefulness in the diagnosis and management of diseases including inflammatory, hereditary, ischemic and compressive lesions of the anterior visual pathway.
Topics: Electroretinography; Humans; Optic Nerve Diseases; Visual Pathways
PubMed: 21915454
DOI: 10.1590/s0004-27492011000300017