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Color Vision: Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of Retinal cone photoreceptors with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).

Vision Training Methods for Sports Concussion Mitigation and Management

1Neurology and Rehabilitative Medicine, University of Cincinnati, 2Division of Sports Medicine, Department of Orthopaedic Surgery, University of Cincinnati, 3Department of Athletics, University of Cincinnati, 4Department of Neurosurgery, University of Cincinnati, 5College of Education, Criminal Justice, and Human Services, University of Cincinnati, 6Division of Sports Medicine, Cincinnati Children's Hospital Medical Center

JoVE 52648


 Behavior

Color Afterimages

JoVE 10194

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

Human color vision is impressive. People with normal color vision can tell apart millions of individual hues. Most amazingly, this ability is achieved with fairly simple hardware.

Part of the power of human color vision comes from a clever bit of engineering in the human brain. There, color perception relies on what is known as an 'opponent system.' This means that the presence of one kind of stimulus is treated as evidence for the absence of another, and vice versa; absence of one kind of stimulus is taken as evidence for the presence of the other. In particular, in the human brain there are cells that fire both when they receive signals to suggest that blue light is present, or when they do not receive signals suggesting yellow light. Similarly, there are cells that fire in the presence of yellow or the absence of blue. Blue and yellow are thus treated as opponent values in one dimension, and can be thought of as negative versus positive values on one axis of a Cartesian plane. If a stimulus is characterized as having a negative value on that axis, it can't also have a positive value. So, if it is characterized as yellow, it can't also be characterized as blue. Similarly, green and red (or really, magenta), o


 Sensation and Perception

Crowding

JoVE 10280

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

Human vision depends on light-sensitive neurons that are arranged in the back of the eye on a tissue called the retina. The neurons, called the rods and cones because of their shapes, are not uniformly distributed on the retina. Instead, there is a region in the center of the retina called the macula where cones are densely packed, and especially so in a central sub-region of the macula called the fovea. Outside the fovea there are virtually no cones, and rod density decreases considerably with greater distance from the fovea. Figure 1 schematizes this arrangement. This kind of arrangement is also replicated in the visual cortex: Many more cells represent stimulation at the fovea compared to the periphery. Figure 1. Schematic depiction of the human eye and the distribution of light-sensitive receptor cells on the retina. The pupil is the opening in the front of the eye that allows light to enter. Light is then focused onto the retina, a neural tissue in the back of the eye that is made of rods and cones, light-sensitive cells. At the center of the retina is the macula, and in


 Sensation and Perception

The Multiple Sclerosis Performance Test (MSPT): An iPad-Based Disability Assessment Tool

1Mellen Center for Multiple Sclerosis Treatment and Research, Cleveland Clinic Foundation, 2Center for Brain Health, Cleveland Clinic Foundation, 3Quantitative Health Sciences, Cleveland Clinic Foundation, 4Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation

JoVE 51318


 Medicine

Eye Exam

JoVE 10149

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

Proper evaluation of the eyes in a general practice setting involves vision testing, orbit inspection, and ophthalmoscopic examination. Before beginning the exam, it is crucial to be familiar with the anatomy and physiology of the eye. The upper eyelid should be slightly over the iris, but it shouldn't cover the pupil when open; the lower lid lies below the iris. The sclera normally appears white or slightly buff in color. The appearance of conjunctiva, a transparent membrane covering the anterior sclera and the inner eyelids, is a sensitive indicator of ocular disorders, such as infections and inflammation. The tear-producing lacrimal gland lies above and lateral to the eyeball. Tears spread down and across the eye to drain medially into two lacrimal puncta before passing into the lacrimal sac and nasolacrimal duct to the nose. The iris divides the anterior from the posterior chamber. Muscles of the iris control the size of the pupil, and muscles of the ciliary body behind it control the focal length of the lens. The ciliary body also produces aqueous humor, which largely determines intraocular pressure (Figure 1). Cranial nerve


 Physical Examinations II

Techniques for Processing Eyes Implanted With a Retinal Prosthesis for Localized Histopathological Analysis

1Bionics Institute, 2Department of Anatomical Pathology, St Vincent's Hospital Melbourne, 3Department of Pathology, University of Melbourne, 4Medical Bionics Department, University of Melbourne

JoVE 50411


 Medicine

Vibratome Sectioning Mouse Retina to Prepare Photoreceptor Cultures

1Department of Genetics, UMR_S 968, Institut de la Vision, 2Department of Visual Information, UMR_S 968, Institut de la Vision, 3Exploratory Team, UMR_S 968, Institut de la Vision, 4Sorbonne Universités, Paris 06, UMR_S 968, Institut de la Vision, 5INSERM, U968, Institut de la Vision, 6CNRS, UMR_7210, Institut de la Vision

JoVE 51954


 Neuroscience

From Voxels to Knowledge: A Practical Guide to the Segmentation of Complex Electron Microscopy 3D-Data

1Life Sciences Division, Lawrence Berkeley National Laboratory, 2Joint Bioenergy Institute, Physical Biosciences Division, Lawrence Berkeley National Laboratory, 3National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory

JoVE 51673


 Bioengineering

Cranial Nerves Exam I (I-VI)

JoVE 10091

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA

During each section of the neurological testing, the examiner uses the powers of observation to assess the patient. In some cases, cranial nerve dysfunction is readily apparent: a patient might mention a characteristic chief complaint (such as loss of smell or diplopia), or a visually evident physical sign of cranial nerve involvement, such as in facial nerve palsy. However, in many cases a patient's history doesn't directly suggest cranial nerve pathologies, as some of them (such as sixth nerve palsy) may have subtle manifestations and can only be uncovered by a careful neurological exam. Importantly, a variety of pathological conditions that are associated with alterations in mental status (such as some neurodegenerative disorders or brain lesions) can also cause cranial nerve dysfunction; therefore, any abnormal findings during a mental status exam should prompt a careful and complete neurological exam. The cranial nerve examination is applied neuroanatomy. The cranial nerves are symmetrical; therefore, while performing the examination, the examiner should compare each side to the other. A physician should approach the examination in a


 Physical Examinations III

Large-Scale Purification of Porcine or Bovine Photoreceptor Outer Segments for Phagocytosis Assays on Retinal Pigment Epithelial Cells

1INSERM, U968, 2Sorbonne Universités, UPMC Paris 06, UMR_S 968, Institut de la Vision, 3CNRS, UMR_7210, 4Department of Biological Sciences, Center for Cancer, Genetic Diseases and Gene Regulation, Fordham University

JoVE 52100


 Immunology and Infection

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

1Hans Berger Department of Neurology, Jena University Hospital, 2Immunology, Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, 3Institute of Diagnostic and Interventional Radiology, Medical Physics Group, Jena University Hospital

JoVE 51274


 Neuroscience

Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs

1Department of Ophthalmology, Seoul National University Bundang Hospital, 2Department of Ophthalmology, College of Medicine, Seoul National University, 3Department of Ophthalmology, Hanyang University Hospital, 4Department of Ophthalmology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 5Department of Clinical Pharmacology, Seoul National University Hospital, 6Department of Clinical Pharmacology, Seoul National University Bundang Hospital

JoVE 53878


 Medicine

Slow-release Drug Delivery through Elvax 40W to the Rat Retina: Implications for the Treatment of Chronic Conditions

1Biotechnology and Applied Clinical Sciences Department, University of L'Aquila, 2ARC Centre of Excellence in Vision Science, 3John Curtin School of Medical Research, Australian National University, 4ANU Medical School, Australian National University

JoVE 51563


 Medicine

Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina

1Institute for Ophthalmic Research, University of Tübingen, 2Graduate School of Cellular & Molecular Neuroscience, University of Tübingen, 3Bernstein Centre for Computational Neuroscience, University of Tübingen, 4Molecular Genetics Laboratory, University of Tübingen, 5Centre for Ophthalmology, University of Tübingen

JoVE 52588


 Neuroscience

Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell

1Woodruff School of Mechanical Engineering, Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 2Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 3Charles Perkins Centre, The University of Sydney, 4Institute of Biophysics, Laboratory of RNA Biology, Chinese Academy of Sciences, 5University of Chinese Academy of Sciences, 6School of Medicine and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University

JoVE 52975


 Bioengineering

The 4 Mountains Test: A Short Test of Spatial Memory with High Sensitivity for the Diagnosis of Pre-dementia Alzheimer's Disease

1Department of Clinical Neurosciences, University of Cambridge, 2Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, 3U.O. Direzione Scientifica, Fondazione IRCCS Istituto Neurologico Carlo Besta, 4Institute of Cognitive Neuroscience, University College London, 5Department of Psychology, University of York

JoVE 54454


 Behavior

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