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Multiple Sclerosis (Houndmills,... Apr 2022Decreased motion perception has been suggested as a marker for visual pathway demyelination in optic neuritis (ON) and/or multiple sclerosis (MS).
BACKGROUND
Decreased motion perception has been suggested as a marker for visual pathway demyelination in optic neuritis (ON) and/or multiple sclerosis (MS).
OBJECTIVES
To examine the influence of neuro-axonal damage on motion perception in MS and neuromyelitis optica spectrum disorders (NMOSD).
METHODS
We analysed motion perception with numbers-from-motion (NFM), visual acuity, (multifocal (mf)) VEP, optical coherence tomography in patients with MS ( = 38, confirmatory cohort = 43), NMOSD ( = 13) and healthy controls ( = 33).
RESULTS
NFM was lower compared with controls in MS ( = -12.37, < 0.001) and NMOSD ( = -34.5, < 0.001). NFM was lower in ON than in non-ON eyes ( = -30.95, = 0.041) in NMOSD, but not MS. In MS and NMOSD, lower NFM was associated with worse visual acuity ( = -139.4, < 0.001/ = -77.2, < 0.001) and low contrast letter acuity ( = 0.99, = 0.002/ = 1.6, < 0.001), thinner peripapillary retinal nerve fibre layer ( = 1.0, < 0.001/ = 0.92, = 0.016) and ganglion cell/inner plexiform layer ( = 64.8, < 0.001/ = 79.5, = 0.006), but not with VEP P100 latencies. In the confirmatory MS cohort, lower NFM was associated with thinner retinal nerve fibre layer ( = 1.351, < 0.001) and increased mfVEP P100 latencies ( = -1.159, < 0.001).
CONCLUSIONS
Structural neuro-axonal visual pathway damage is an important driver of motion perception impairment in MS and NMOSD.
Topics: Humans; Motion Perception; Multiple Sclerosis; Neuromyelitis Optica; Optic Neuritis; Tomography, Optical Coherence; Visual Pathways
PubMed: 34379018
DOI: 10.1177/13524585211032801 -
BMC Ophthalmology Mar 2022RNFL thickness measured by optical coherence tomography (OCT) and visual pathway measured by diffusion tensor imaging (DTI) can be used to predict visual field recovery,...
A pilot study of combined optical coherence tomography and diffusion tensor imaging method for evaluating microstructural change in the visual pathway of pituitary adenoma patients.
BACKGROUND
RNFL thickness measured by optical coherence tomography (OCT) and visual pathway measured by diffusion tensor imaging (DTI) can be used to predict visual field recovery, respectively. However, the relationship between RNFL thickness and visual pathway injury in patients with pituitary adenoma (PA) remains unclear. This study aims to evaluate the combining DTI and OCT methods in observing the microstructural change in the visual pathway in patients with PA.
METHODS
Twenty-nine patients who were diagnosed with PA were included in the study group, and 29 healthy subjects were included as the control group. OCT detected the thickness of circumpapillary retinal nerve fiber layer (CP-RNFL) and ganglion cell layer (GCL). DTI measured the values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Correlation between CP-RNFL and GCL thickness and FA and ADC values was analyzed in the study group.
RESULTS
Compared with the control group, the FA values of the bilateral optic nerve, chiasma, bilateral optic tract, and left optic radiation in the study group were reduced, and the ADC values of the bilateral optic nerve and optic chiasma were increased. Correlation analysis showed that the FA value of the optic chiasma was positively correlated with the average thickness of RNFL, the CP-RNFL thickness in the nasal and temporal retinal quadrants in both eyes, as well as the thickness of macular ring GCL in the nasal, supra, and inferior quadrants. The FA values of the optic nerve, optic chiasma, optic tract, and optic radiation were positively correlated with CP-RNFL thickness in the nasal and temporal quadrants.
CONCLUSION
Combined DTI and OCT can provide a comprehensive understanding of the microscopic changes in the structure and function of the whole visual pathway in patients with PA.
Topics: Diffusion Tensor Imaging; Humans; Pilot Projects; Pituitary Neoplasms; Tomography, Optical Coherence; Visual Pathways
PubMed: 35279128
DOI: 10.1186/s12886-022-02320-2 -
AJNR. American Journal of Neuroradiology May 2016Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying... (Review)
Review
Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying "organic" brain disease. Thus, patients with visual hallucinations are often referred for imaging of the brain. This article presents a pragmatic approach for the radiologist reviewing such imaging. Because conditions that can present with visual hallucinations are legion, a familiarity with the features of the hallucinations themselves, which can serve as clues to the underlying cause, can be helpful in interpreting such cases. We consider the nature of visual hallucinations and the mechanisms underlying their formation. We then provide a framework to guide the search for their cause, first in terms of focal lesions along the visual pathway and then global conditions affecting >1 region.
Topics: Brain; Brain Diseases; Female; Hallucinations; Humans; Male; Neuroimaging; Visual Pathways
PubMed: 26744445
DOI: 10.3174/ajnr.A4636 -
The Journal of Neuroscience : the... Aug 2019Visual information reaches the cerebral cortex through parallel ON and OFF pathways that signal the presence of light and dark stimuli in visual scenes. We have... (Comparative Study)
Comparative Study
Visual information reaches the cerebral cortex through parallel ON and OFF pathways that signal the presence of light and dark stimuli in visual scenes. We have previously demonstrated that optical blur reduces visual salience more for light than dark stimuli because it removes the high spatial frequencies from the stimulus, and low spatial frequencies drive weaker ON than OFF cortical responses. Therefore, we hypothesized that sustained optical blur during brain development should weaken ON cortical pathways more than OFF, increasing the dominance of darks in visual perception. Here we provide support for this hypothesis in humans with anisometropic amblyopia who suffered sustained optical blur early after birth in one of the eyes. In addition, we show that the dark dominance in visual perception also increases in strabismic amblyopes that have their vision to high spatial frequencies reduced by mechanisms not associated with optical blur. Together, we show that amblyopia increases visual dark dominance by 3-10 times and that the increase in dark dominance is strongly correlated with amblyopia severity. These results can be replicated with a computational model that uses greater luminance/response saturation in ON than OFF pathways and, as a consequence, reduces more ON than OFF cortical responses to stimuli with low spatial frequencies. We conclude that amblyopia affects the ON cortical pathway more than the OFF, a finding that could have implications for future amblyopia treatments. Amblyopia is a loss of vision that affects 2-5% of children across the world and originates from a deficit in visual cortical circuitry. Current models assume that amblyopia affects similarly ON and OFF visual pathways, which signal light and dark features in visual scenes. Against this current belief, here we demonstrate that amblyopia affects the ON visual pathway more than the OFF, a finding that could have implications for new amblyopia treatments targeted at strengthening a weak ON visual pathway.
Topics: Adolescent; Adult; Amblyopia; Brain; Cerebral Cortex; Darkness; Eye; Female; Fixation, Ocular; Humans; Light; Male; Middle Aged; Neuronal Plasticity; Photic Stimulation; Psychophysics; Thalamus; Vision, Monocular; Visual Acuity; Visual Pathways; Young Adult
PubMed: 31189574
DOI: 10.1523/JNEUROSCI.3215-18.2019 -
Sheng Li Xue Bao : [Acta Physiologica... Apr 2022How the brain perceives objects and classifies perceived objects is one of the important goals of visual cognitive neuroscience. Previous research has shown that when we...
How the brain perceives objects and classifies perceived objects is one of the important goals of visual cognitive neuroscience. Previous research has shown that when we see objects, the brain's ventral visual pathway recognizes and classifies them, leading to different ways of interacting with them. In this paper, we summarize the latest research progress of the ventral visual pathway related to the visual classification of objects. From the perspective of the neural representation of objects and its underlying mechanisms in the visual cortex, we summarize the current research status of the two important organizational dimensions of object animacy and real-world size, provide new insights, and point out the direction of further research.
Topics: Brain Mapping; Magnetic Resonance Imaging; Pattern Recognition, Visual; Photic Stimulation; Visual Cortex; Visual Pathways
PubMed: 35503077
DOI: No ID Found -
BMC Biology Sep 2010The visual pathway is tasked with processing incoming signals from the retina and converting this information into adaptive behavior. Recent studies of the larval... (Review)
Review
The visual pathway is tasked with processing incoming signals from the retina and converting this information into adaptive behavior. Recent studies of the larval zebrafish tectum have begun to clarify how the 'micro-circuitry' of this highly organized midbrain structure filters visual input, which arrives in the superficial layers and directs motor output through efferent projections from its deep layers. The new emphasis has been on the specific function of neuronal cell types, which can now be reproducibly labeled, imaged and manipulated using genetic and optical techniques. Here, we discuss recent advances and emerging experimental approaches for studying tectal circuits as models for visual processing and sensorimotor transformation by the vertebrate brain.
Topics: Animals; Models, Neurological; Nerve Net; Neurons; Superior Colliculi; Visual Pathways; Visual Perception; Zebrafish
PubMed: 20920150
DOI: 10.1186/1741-7007-8-126 -
Journal of Vision Feb 2020The parallel pathways of the human visual system differ in their tuning to luminance, color, and spatial frequency. These attunements recently have been shown to...
The parallel pathways of the human visual system differ in their tuning to luminance, color, and spatial frequency. These attunements recently have been shown to propagate to differential processing of higher-order stimuli, facial threat cues, in the magnocellular (M) and parvocellular (P) pathways, with greater sensitivity to clear and ambiguous threat, respectively. The role of the third, koniocellular (K) pathway in facial threat processing, however, remains unknown. To address this gap in knowledge, we briefly presented peripheral face stimuli psychophysically biased towards M, P, or K pathways. Observers were instructed to report via a key-press whether the face was angry or neutral while their eye movements and manual responses were recorded. We found that short-latency saccades were made more frequently to faces presented in the K channel than to P or M channels. Saccade latencies were not significantly modulated by expressive and identity cues. In contrast, manual response latencies and accuracy were modulated by both pathway biasing and by interactions of facial expression with facial masculinity, such that angry male faces elicited the fastest, and angry female faces, the least accurate, responses. We conclude that face stimuli can evoke fast saccadic and manual responses when projected to the K pathway.
Topics: Adult; Cues; Facial Expression; Female; Humans; Male; Reaction Time; Saccades; Visual Pathways; Young Adult
PubMed: 32097485
DOI: 10.1167/jov.20.2.9 -
Neurotherapeutics : the Journal of the... Apr 2021Glaucoma is a neurodegenerative disease that causes progressive, irreversible vision loss. Currently, intraocular pressure (IOP) is the only modifiable risk factor for...
Glaucoma is a neurodegenerative disease that causes progressive, irreversible vision loss. Currently, intraocular pressure (IOP) is the only modifiable risk factor for glaucoma. However, glaucomatous degeneration may continue despite adequate IOP control. Therefore, there exists a need for treatment that protects the visual system, independent of IOP. This study sought, first, to longitudinally examine the neurobehavioral effects of different magnitudes and durations of IOP elevation using multi-parametric magnetic resonance imaging (MRI), optokinetics and histology; and, second, to evaluate the effects of oral citicoline treatment as a neurotherapeutic in experimental glaucoma. Eighty-two adult Long Evans rats were divided into six groups: acute (mild or severe) IOP elevation, chronic (citicoline-treated or untreated) IOP elevation, and sham (acute or chronic) controls. We found that increasing magnitudes and durations of IOP elevation differentially altered structural and functional brain connectivity and visuomotor behavior, as indicated by decreases in fractional anisotropy in diffusion tensor MRI, magnetization transfer ratios in magnetization transfer MRI, T1-weighted MRI enhancement of anterograde manganese transport, resting-state functional connectivity, visual acuity, and neurofilament and myelin staining along the visual pathway. Furthermore, 3 weeks of oral citicoline treatment in the setting of chronic IOP elevation significantly reduced visual brain integrity loss and visual acuity decline without altering IOP. Such effects sustained after treatment was discontinued for another 3 weeks. These results not only illuminate the close interplay between eye, brain, and behavior in glaucomatous neurodegeneration, but also support a role for citicoline in protecting neural tissues and visual function in glaucoma beyond IOP control.
Topics: Animals; Behavior, Animal; Cytidine Diphosphate Choline; Diffusion Tensor Imaging; Eye Movement Measurements; Female; Glaucoma; Intraocular Pressure; Multiparametric Magnetic Resonance Imaging; Neural Pathways; Neurodegenerative Diseases; Nootropic Agents; Ocular Hypertension; Optic Nerve; Proton Magnetic Resonance Spectroscopy; Psychomotor Performance; Rats; Severity of Illness Index; Time Factors; Visual Acuity; Visual Pathways
PubMed: 33846961
DOI: 10.1007/s13311-021-01033-6 -
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 -
Frontiers in Neural Circuits 2019Understanding the mechanisms of vision in health and disease requires knowledge of the anatomy and physiology of the eye and the neural pathways relevant to visual... (Review)
Review
Understanding the mechanisms of vision in health and disease requires knowledge of the anatomy and physiology of the eye and the neural pathways relevant to visual perception. As such, development of imaging techniques for the visual system is crucial for unveiling the neural basis of visual function or impairment. Magnetic resonance imaging (MRI) offers non-invasive probing of the structure and function of the neural circuits without depth limitation, and can help identify abnormalities in brain tissues . Among the advanced MRI techniques, manganese-enhanced MRI (MEMRI) involves the use of active manganese contrast agents that positively enhance brain tissue signals in T1-weighted imaging with respect to the levels of connectivity and activity. Depending on the routes of administration, accumulation of manganese ions in the eye and the visual pathways can be attributed to systemic distribution or their local transport across axons in an anterograde fashion, entering the neurons through voltage-gated calcium channels. The use of the paramagnetic manganese contrast in MRI has a wide range of applications in the visual system from imaging neurodevelopment to assessing and monitoring neurodegeneration, neuroplasticity, neuroprotection, and neuroregeneration. In this review, we present four major domains of scientific inquiry where MEMRI can be put to imperative use - deciphering neuroarchitecture, tracing neuronal tracts, detecting neuronal activity, and identifying or differentiating glial activity. We deliberate upon each category studies that have successfully employed MEMRI to examine the visual system, including the delivery protocols, spatiotemporal characteristics, and biophysical interpretation. Based on this literature, we have identified some critical challenges in the field in terms of toxicity, and sensitivity and specificity of manganese enhancement. We also discuss the pitfalls and alternatives of MEMRI which will provide new avenues to explore in the future.
Topics: Animals; Brain; Contrast Media; Humans; Magnetic Resonance Imaging; Manganese; Neuroimaging; Neurosciences; Ophthalmology; Visual Pathways
PubMed: 31156399
DOI: 10.3389/fncir.2019.00035