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Ruiz T, Brown S, Farivar R. Graph Analysis of the Visual Cortical Network during Naturalistic Movie Viewing Reveals Increased Integration and Decreased Segregation Following Mild TBI. Vision (Basel) 2024; 8:33. [PMID: 38804354 PMCID: PMC11130927 DOI: 10.3390/vision8020033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/03/2024] [Accepted: 04/18/2024] [Indexed: 05/29/2024] Open
Abstract
Traditional neuroimaging methods have identified alterations in brain activity patterns following mild traumatic brain injury (mTBI), particularly during rest, complex tasks, and normal vision. However, studies using graph theory to examine brain network changes in mTBI have produced varied results, influenced by the specific networks and task demands analyzed. In our study, we employed functional MRI to observe 17 mTBI patients and 54 healthy individuals as they viewed a simple, non-narrative underwater film, simulating everyday visual tasks. This approach revealed significant mTBI-related changes in network connectivity, efficiency, and organization. Specifically, the mTBI group exhibited higher overall connectivity and local network specialization, suggesting enhanced information integration without overwhelming the brain's processing capabilities. Conversely, these patients showed reduced network segregation, indicating a less compartmentalized brain function compared to healthy controls. These patterns were consistent across various visual cortex subnetworks, except in primary visual areas. Our findings highlight the potential of using naturalistic stimuli in graph-based neuroimaging to understand brain network alterations in mTBI and possibly other conditions affecting brain integration.
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Affiliation(s)
- Tatiana Ruiz
- Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC H4A 0A4, Canada (S.B.)
- Research Institute of the McGill University Health Center, Montreal, QC H3G 1A4, Canada
| | - Shael Brown
- Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC H4A 0A4, Canada (S.B.)
- Research Institute of the McGill University Health Center, Montreal, QC H3G 1A4, Canada
| | - Reza Farivar
- Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC H4A 0A4, Canada (S.B.)
- Research Institute of the McGill University Health Center, Montreal, QC H3G 1A4, Canada
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2
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Rauchman SH, Zubair A, Jacob B, Rauchman D, Pinkhasov A, Placantonakis DG, Reiss AB. Traumatic brain injury: Mechanisms, manifestations, and visual sequelae. Front Neurosci 2023; 17:1090672. [PMID: 36908792 PMCID: PMC9995859 DOI: 10.3389/fnins.2023.1090672] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Traumatic brain injury (TBI) results when external physical forces impact the head with sufficient intensity to cause damage to the brain. TBI can be mild, moderate, or severe and may have long-term consequences including visual difficulties, cognitive deficits, headache, pain, sleep disturbances, and post-traumatic epilepsy. Disruption of the normal functioning of the brain leads to a cascade of effects with molecular and anatomical changes, persistent neuronal hyperexcitation, neuroinflammation, and neuronal loss. Destructive processes that occur at the cellular and molecular level lead to inflammation, oxidative stress, calcium dysregulation, and apoptosis. Vascular damage, ischemia and loss of blood brain barrier integrity contribute to destruction of brain tissue. This review focuses on the cellular damage incited during TBI and the frequently life-altering lasting effects of this destruction on vision, cognition, balance, and sleep. The wide range of visual complaints associated with TBI are addressed and repair processes where there is potential for intervention and neuronal preservation are highlighted.
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Affiliation(s)
| | - Aarij Zubair
- NYU Long Island School of Medicine, Mineola, NY, United States
| | - Benna Jacob
- NYU Long Island School of Medicine, Mineola, NY, United States
| | - Danielle Rauchman
- Department of Neuroscience, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Aaron Pinkhasov
- NYU Long Island School of Medicine, Mineola, NY, United States
| | | | - Allison B Reiss
- NYU Long Island School of Medicine, Mineola, NY, United States
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3
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Brau JM, Sugarman A, Rothlein D, DeGutis J, Esterman M, Fortenbaugh FC. The impact of image degradation and temporal dynamics on sustained attention. J Vis 2022; 22:8. [PMID: 35297998 PMCID: PMC8944397 DOI: 10.1167/jov.22.4.8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Many clinical populations that have sustained attention deficits also have visual deficits. Therefore, it is necessary to understand how the quality of visual input and different forms of image degradation can contribute to worse performance on sustained attention tasks, particularly those with dynamic and complex visual stimuli. This study investigated the impact of image degradation on an adapted version of the gradual-onset continuous performance task (gradCPT), where participants must discriminate between gradually fading city and mountain scenes. Thirty-six normal-vision participants completed the task, which featured two blocks of six resolution and contrast levels. Subjects either completed a version with gradually fading or static image presentations. The results show decreases in image resolution impair performance under both types of temporal dynamics, whereas performance is only impaired under gradual temporal dynamics for decreases in image contrast. Image similarity analyses showed that performance has a higher association with an observer's ability to gather an image's global spatial layout (i.e. gist) than local variations in pixel luminance, particularly under gradual image presentation. This work suggests that gradually fading attention paradigms are sensitive to deficits in primary visual function, potentially leading to these issues being misinterpreted as attentional failures.
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Affiliation(s)
- Julia M Brau
- Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,
| | - Alexander Sugarman
- Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,
| | - David Rothlein
- Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,Boston Attention and Learning Lab (BALLAB), VA Boston Healthcare System, Boston, MA, USA.,National Center for PTSD, VA Boston Healthcare System, Boston, MA, USA.,
| | - Joseph DeGutis
- Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,Boston Attention and Learning Lab (BALLAB), VA Boston Healthcare System, Boston, MA, USA.,Department of Psychiatry, Harvard Medical School, Cambridge, MA, USA.,
| | - Michael Esterman
- National Center for PTSD, VA Boston Healthcare System, Boston, MA, USA.,Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,Boston Attention and Learning Lab (BALLAB), VA Boston Healthcare System, Boston, MA, USA.,Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA.,
| | - Francesca C Fortenbaugh
- Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, USA.,Department of Psychiatry, Harvard Medical School, Cambridge, MA, USA.,
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Benassi M, Frattini D, Garofalo S, Bolzani R, Pansell T. Visuo-motor integration, vision perception and attention in mTBI patients. Preliminary findings. PLoS One 2021; 16:e0250598. [PMID: 33905440 PMCID: PMC8078787 DOI: 10.1371/journal.pone.0250598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 04/11/2021] [Indexed: 11/19/2022] Open
Abstract
Patients with mild traumatic brain injuries (mTBI) often report difficulties in motor coordination and visuo-spatial attention. However, the consequences of mTBI on fine motor and visuo-motor coordination are still not well understood. We aimed to evaluate whether mTBI had a concomitant effect on fine motor ability and visuo-motor integration and whether this is related to visual perception and visuo-spatial attention impairments, including patients at different symptoms stage. Eleven mTBI patients (mean age 22.8 years) and ten healthy controls participated in the study. Visuo-motor integration of fine motor abilities and form recognition were measured with the Beery-Buktenica Developmental Test of Visual-Motor Integration test, motion perception was evaluated with motion coherence test, critical flicker fusion was measured with Pocket CFF tester. Visuo-spatial was assessed with the Ruff 2 & 7 Selection Attention Test. mTBI patients showed reduced visuo-motor integration, form recognition, and motor deficits as well as visuo-spatial attention impairment, while motion perception and critical flicker fusion were not impaired. These preliminary findings suggest that the temporary brain insults deriving from mTBI compromise fine motor skills, visuomotor integration, form recognition, and visuo-spatial attention. The impairment in visuo-motor coordination was associated with speed in visuo-attention and correlated with symptoms severity while motor ability was correlated with time since concussion. Given the strong correlation between visuomotor coordination and symptom severity, further investigation with a larger sample seems warranted. Since there appeared to be differences in motor skills with respect to symptom stage, further research is needed to investigate symptom profiles associated with visuomotor coordination and fine motor deficits in mTBI patients.
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Affiliation(s)
| | - Davide Frattini
- Department of Psychology, University of Bologna, Bologna, Italy
| | - Sara Garofalo
- Department of Psychology, University of Bologna, Bologna, Italy
| | - Roberto Bolzani
- Department of Psychology, University of Bologna, Bologna, Italy
| | - Tony Pansell
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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5
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Gao H, Miles TP, Troche R, Murdoch DM, Koefoed VF, Cason JB. Quality of Vision Following LASIK and PRK-MMC for Treatment of Myopia. Mil Med 2021; 187:e1051-e1058. [PMID: 33629728 DOI: 10.1093/milmed/usab071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 01/13/2021] [Accepted: 02/09/2021] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION Femtosecond-assisted thin flap, laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) are the two most common refractive surgical procedures used to enhance visual capability in the U.S military. The purposes of the study were to examine effects on quality of vision following LASIK and PRK-MMC using a novel computer-based quick contrast sensitivity function (qCSF) test. MATERIALS AND METHODS This prospective clinical study included 58 active duty U.S. military service members who elected LASIK (n = 29) or PRK-MMC (n = 29) refractive surgery for myopia (nearsightedness) treatment. Monocular photopic and mesopic quality of vision of the right eyes in spectacle correction preoperatively and unaided right eyes at four postoperative follow-up visits (1 week, 2 weeks, 1 month, and 3 months) were examined using the qCSF device. Two qCSF parameters, area under a log CSF (AULCSF) between 1.5 and 18 cycles per degree, and CSF cutoff acuity (CSF Acuity), were collected using a 50-trial setting at a 4-m testing distance. General linear model (GLM) Repeated-measures Analysis of Covariance was used to examine effects on quality of vision following LASIK and PRK-MMC. Post hoc testing with Bonferroni correction was used for pairwise comparisons, and preoperative cylinder refraction was used as a covariate. Two-tailed independent t-test was used to compare preoperative and postoperative parameters between LASIK and PRK-MMC. Pearson's correlation, Bland-Altman plots, and multiple linear regression were used to examine the relationship among the qCSF and other vision tests. RESULTS Quality of vision, AULCSF, and CSF Acuity returned to the preoperative baseline at postoperative 2 weeks under mesopic condition and at postoperative 1 month under photopic condition after PRK-MMC. In comparison, photopic and mesopic quality of vision were not significantly different from the baseline at any of the four postoperative visits following LASIK. Changes of CSF Acuity from the baseline after LASIK were significantly better under photopic than mesopic condition by 0.067 ± 0.014 logarithm of the minimum angle of resolution (logMAR); P < .001). Quality of vision was not significantly different between the LASIK and PRK-MMC groups at postoperative 1 and 3 months. When predicting photopic AULCSF (overall model fit R2 = 0.47), 5% contrast acuity (beta = -0.43), visual acuity in 100% contrast (beta = -0.18), and residual refraction in spherical equivalent (beta = 0.20) were significant predictors (P ≤ .001), while high-order aberrations (beta = -0.07, P = .22) were not significant predictors. Visual acuity (beta = -0.12, P = .07) and high-order aberrations (beta = -0.04, P = .58) were not significant predictors of mesopic AULCSF. Bland-Altman plots show that photopic CSF Acuity and visual acuity had a mean difference of 0.19 ± 0.01 logMAR with limits of agreement (LOAs) at -0.01 and 0.39 logMAR. Photopic CSF Acuity and 5% contrast acuity had a mean difference of -0.06 ± 0.01 logMAR with LOAs at -0.33 and 0.21 logMAR. CONCLUSION Quality of vision recovers at postoperative 1 week after LASIK and at postoperative 1 month after PRK-MMC. The standard black-on-white high-contrast, chart-based visual acuity test is weak in predicting quality of vision. The qCSF detects mild-to-moderate visual changes and is suitable for quality of vision assessment following refractive eye surgery.
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Affiliation(s)
- Hong Gao
- Tri-Service Vision Conservation & Readiness Program, Army Public Health Center, Aberdeen Proving Ground, MD 21010-5403, USA
| | - Tyler P Miles
- Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, CA 92134, USA
| | - Ray Troche
- Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, CA 92134, USA
| | - Donna M Murdoch
- Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, CA 92134, USA
| | - Vilhelm F Koefoed
- Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, CA 92134, USA.,Norwegian Armed Forces, Joint Medical Services, Department of Global Public Health and Primary Care, University of Bergen Faculty of Medicine and Dentistry, Bergen, Norway
| | - John B Cason
- Navy Refractive Surgery Center, Naval Medical Center San Diego, San Diego, CA 92134, USA
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Desenvolvimento e validação de medidas psicofísicas de sensibilidade ao contraste de segunda-ordem. PSICO 2020. [DOI: 10.15448/1980-8623.2020.4.38077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A medida de sensibilidade ao contraste (SC) de primeira ordem é frequentemente utilizada para avaliação da percepção espacial. Nosso objetivo foi desenvolver e validar um teste de SC de segunda ordem para aplicação clínica. Modificações metodológicas foram realizadas na rotina psicofísica para redução do tempo de testagem e no primeiro experimento validamos a nova metodologia. Em um segundo experimento, dezesseis participantes foram testados nas mesmas condições do primeiro experimento. As medidas de consistência interna por alfa de Cronbach foram robustas para a medida de primeira ordem sendo α= 0,788, segunda ordem por ruído branco α= 0,668 e por ruído rosa α= 0,717. O desenvolvimento e validação deste novo experimento para medidas de SC de segunda ordem permitirá avançar nos estudos dos mecanismos básicos da percepção de espaço para estímulos complexos, assim como a aplicação clínica em diversas doenças.
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7
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Ruiz T, Baldwin AS, Spiegel DP, Hess R, Farivar R. Increased Noise in Cortico-Cortical Integration After Mild TBI Measured With the Equivalent Noise Technique. Front Neurol 2019; 10:767. [PMID: 31428031 PMCID: PMC6689961 DOI: 10.3389/fneur.2019.00767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/02/2019] [Indexed: 11/13/2022] Open
Abstract
The bulk of deficits accompanying mild traumatic brain injury (mTBI) is understood in terms of cortical integration—mnemonic, attentional, and cognitive disturbances are believed to involve integrative action across brain regions. Independent of integrative disturbances, mTBI may increase cortical noise, and this has not been previously considered. High-level integrative deficits are exceedingly difficult to measure and model, motivating us to utilize a tightly-controlled task within an established quantitative model to separately estimate internal noise and integration efficiency. First, we utilized a contour integration task modeled as a cortical-integration process involving multiple adjacent cortical columns in early visual areas. Second, we estimated internal noise and integration efficiency using the linear amplifier model (LAM). Fifty-seven mTBI patients and 24 normal controls performed a 4AFC task where they had to identify a valid contour amongst three invalid contours. Thresholds for contour amplitude were measured adaptively across three levels of added external orientation noise. Using the LAM, we found that mTBI increased internal noise without affecting integration efficiency. mTBI also caused hemifield bias differences, and efficiency was related to a change of visual habits. Using a controlled task reflecting cortical integration within the equivalent noise framework empowered us to detect increased computational noise that may be at the heart of mTBI deficits. Our approach is highly sensitive and translatable to rehabilitative efforts for the mTBI population, while also implicating a novel hypothesis of mTBI effects on basic visual processing—namely that cortical integration is maintained at the cost of increased internal noise.
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Affiliation(s)
- Tatiana Ruiz
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Alex S Baldwin
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Daniel P Spiegel
- Vision Sciences, Essilor R&D, Center for Innovation and Technology, Singapore, Singapore
| | - Robert Hess
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Reza Farivar
- Research Institute of the McGill University Health Center, Montreal, QC, Canada
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8
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Alnawmasi MM, Chakraborty A, Dalton K, Quaid P, Dunkley BT, Thompson B. The effect of mild traumatic brain injury on the visual processing of global form and motion. Brain Inj 2019; 33:1354-1363. [PMID: 31317788 DOI: 10.1080/02699052.2019.1641842] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cortical visual processing involves the ventral stream (form perception) and the dorsal stream (motion perception). We assessed whether mild traumatic brain injury (TBI) differentially affects these two streams. Eleven adults with mild TBI (28 ± 9 yrs, 17 ± 5 months post injury) and 25 controls (25 ± 5 yrs) participated. Participants completed tests of global processing involving Glass patterns (form) and random dot kinematograms (motion), measurement of contrast thresholds for motion direction discrimination, a comprehensive vision screening and the Post-Concussion Symptom Inventory (PCSI). Our results showed that the mild TBI group had significantly higher (worse) global form (mean ± SD: TBI 25 ± 6%, control 21 ± 5%) and motion (TBI 14 ± 7%, control 11 ± 3%) coherence thresholds than controls. The magnitude of the mild TBI group deficit did not differ between the two tasks. Contrast thresholds for motion direction discrimination did not differ between the groups, but were positively correlated with PCSI score (r2 = 0.51. p = 0.01) in the mild TBI group. The mild TBI group had worse outcomes than controls for all clinical measurements of vision except distance visual acuity. In conclusion, mild TBI affects processing in both the dorsal and ventral cortical processing streams equally. In addition, spatiotemporal contrast sensitivity may be related to the symptoms of mild TBI.
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Affiliation(s)
- Mohammed M Alnawmasi
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada.,b College of Applied Medical Sciences, Department of Optometry, Qassim University , Buraidah , Saudi Arabia
| | - Arijit Chakraborty
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada
| | - Kristine Dalton
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada
| | - Patrick Quaid
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada.,c VUE Cubed Vision Rehabilitation Clinics, The Guelph Vision Therapy Centre , Guelph , ON , Canada
| | - Benjamin T Dunkley
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada.,d Diagnostic Imaging, Hospital for Sick Children; Neurosciences & Mental Health, Hospital for Sick Children Research Institute; Medical Imaging, University of Toronto , Toronto , Canada
| | - Benjamin Thompson
- a School of Optometry and Vision Science, University of Waterloo , Waterloo , Canada
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9
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Xu X, Chen Q, Xu R. The Study of Spatial Frequency Channels for Human Visual System. INT J PATTERN RECOGN 2019. [DOI: 10.1142/s0218001419550073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Similar to auditory perception of sound system, color perception of the human visual system also presents a multi-frequency channel property. In order to study the multi-frequency channel mechanism of how the human visual system processes color information, the paper proposed a psychophysical experiment to measure the contrast sensitivities based on 17 color samples of 16 spatial frequencies on CIELAB opponent color space. Correlation analysis was carried out on the psychophysical experiment data, and the results show obvious linear correlations of observations for different spatial frequencies of different observers, which indicates that a linear model can be used to model how human visual system processes spatial frequency information. The results of solving the model based on the experiment data of color samples show that 9 spatial frequency tuning curves can exist in human visual system with each lightness, R–G and Y–B color channel and each channel can be represented by 3 tuning curves, which reflect the “center-around” form of the human visual receptive field. It is concluded that there are 9 spatial frequency channels in human vision system. The low frequency tuning curve of a narrow-frequency bandwidth shows the characteristics of lower level receptive field for human vision system, the medium frequency tuning curve shows a low pass property of the change of medium frequent colors and the high frequency tuning curve of a width-frequency bandwidth, which has a feedback effect on the low and medium frequency channels and shows the characteristics of higher level receptive field for human vision system, which represents the discrimination of details.
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Affiliation(s)
- Xiangyang Xu
- School of Communication, Shenzhen Polytechnic, Guangdong Shenzhen 518055, P. R. China
| | - Qiao Chen
- School of Communication, Shenzhen Polytechnic, Guangdong Shenzhen 518055, P. R. China
| | - Ruixin Xu
- School of Communication, Shenzhen Polytechnic, Guangdong Shenzhen 518055, P. R. China
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Jennings BJ, Schmidtmann G, Wehbé F, Kingdom FAA, Farivar R. Detection of distortions in images of natural scenes in mild traumatic brain injury patients. Vision Res 2019; 161:12-17. [PMID: 31129288 DOI: 10.1016/j.visres.2019.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/09/2019] [Accepted: 05/12/2019] [Indexed: 10/26/2022]
Abstract
Mild traumatic brain injuries (mTBI) frequently lead to the impairment of visual functions including blurred and/or distorted vision, due to the disruption of visual cortical mechanisms. Previous mTBI studies have focused on specific aspects of visual processing, e.g., stereopsis, using artificial, low-level, stimuli (e.g., Gaussian patches and gratings). In the current study we investigated high-level visual processing by employing images of real world natural scenes as our stimuli. Both an mTBI group and control group composed of healthy observers were tasked with detecting sinusoidal distortions added to the natural scene stimuli as a function of the distorting sinusoid's spatial frequency. It was found that the mTBI group were equally as sensitive to high frequency distortions as the control group. However, sensitivity decreased more rapidly with decreasing distortion frequency in the mTBI group relative to the controls. These data reflect a deficit in the mTBI group to spatially integrate over larger regions of the scene.
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Affiliation(s)
- B J Jennings
- Centre for Cognitive Neuroscience, Department of Life Sciences, College of Health and Life Sciences, Brunel University, London, UK; McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montreal, Canada.
| | - G Schmidtmann
- McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montreal, Canada; Eye & Vision Research Group, Department of Optometry, University of Plymouth, Plymouth, UK
| | - F Wehbé
- McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montreal, Canada
| | - F A A Kingdom
- McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montreal, Canada
| | - R Farivar
- McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montreal, Canada; Traumatic Brain Injury Program, Research Institute of the McGill University Health Centre, Montreal, Canada
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11
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Second-order visual sensitivity in the aging population. Aging Clin Exp Res 2019; 31:705-716. [PMID: 30168100 DOI: 10.1007/s40520-018-1018-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/31/2018] [Indexed: 10/28/2022]
Abstract
Most visual and cognitive functions are affected by aging over the lifespan. In this study, our aim was to investigate the loss in sensitivity to different classes of second-order stimuli-a class of stimuli supposed to be mainly processed in extrastriate cortex-in the aging population. These stimuli will then allow one to identify specific cortical deficit independently of visibility losses in upstream parts of the visual pathway. For this purpose, we measured the sensitivity to first-order stimuli and second-order stimuli: orientation-modulated, motion-modulated or contrast-modulated as a function of spatial frequency in 50 aged participants. Overall, we observed a sensitivity loss for all classes of stimuli, but this loss differentially affects the three classes of second-order stimuli tested. It involves all modulation spatial frequencies in the case of motion modulation, but just high modulation spatial frequencies in the case of contrast- and orientation modulations. These observations imply that aging selectively affects the sensitivity to second-order stimuli depending on their type. Since there is evidence that these different second-order stimuli are processed in different regions of extrastriate cortex, this result may suggest that some visual cortical areas are more susceptible to aging effects than others.
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12
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Spotlight on Neurotrauma Research in Canada's Leading Academic Centers. J Neurotrauma 2018; 35:1986-2004. [PMID: 30074875 DOI: 10.1089/neu.2018.29017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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