Biological Psychology Links

Laser light has been used to remotely control gene therapy in rats. This mechanism will help make gene therapy more effective by allowing the precise time and location at which new genes are activated to be controlled, meaning specific tissues can be targeted while healthy tissues are left alone. Lasers have been used in the past to perforate cells for gene therapy in cultured cells. But the new research – activating marker genes in the eyes of rats – is more sophisticated and the first time lasers have been used for gene therapy in live animals. Kazunori Kataoka, at the University of Tokyo, Japan, and colleagues developed a photosensitive molecular complex that could be activated in rats’ eyes by irradiating them with visible light from a low power laser. The synthetic complex is designed to deliver foreign DNA by carrying it past the cell membrane – a process known as transfection. The complex consists of three components: a photosensitive anionic dendrimer, which provides the triggering mechanism, and a cationic peptide which drives the third component, its DNA payload, towards the nucleus of a cell after it has been released. The complex enters the cell by a process known as endocytosis, where the cell's plasma membrane envelops the complex at its surface and draws it into the cell. The membrane around the complex then detaches from the cell's membrane to form a bubble containing the complex within the cell. © Copyright Reed Business Information Ltd.

The first images ever made of retinas in living people reveal surprising variation from one person to the next. Yet somehow our perceptions don't vary as might be expected. As they took pictures of the thousands of cells responsible for detecting color in the deepest layer of the eye, scientists found that our eyes are wired differently. Yet we all — with the exception of the colorblind — identify colors similarly. The results suggest that the brain plays an even more significant role than thought in deciding what we see. The eye, responsible for receiving visual images, is wrapped in three layers of tissue. The innermost layer, the retina, is responsible for sensing color and sending information to the brain. The retina contains light receptors known as cones and rods. These receptors receive light, convert it to chemical energy, and activate the nerves that send messages to the brain. The rods are in charge of perceiving size, brightness and shape of images, whereas color vision and fine details are the responsibility of the cones. © 2005 MSNBC.com © 2005 Microsoft

A protein associated with a disorder that causes deafness and blindness in people may be a key to unraveling one of the foremost mysteries of how we hear, says a study in the June 28 issue of the Journal of Neuroscience. Scientists with the National Institute on Deafness and Other Communication Disorders (NIDCD), one of the National Institutes of Health (NIH), and the University of Sussex, Brighton, United Kingdom, have identified protocadherin-15 as a likely player in the moment-of-truth reaction in which sound is converted into electrical signals. (Protocadherin-15 is a protein made by a gene that causes one form of type 1 Usher syndrome, the most common cause of deaf-blindness in humans.) The findings will not only provide insight into how hearing takes place at the molecular level, but also may help us figure out why some people temporarily lose their hearing after being exposed to loud noise, only to regain it a day or two later. “These findings offer a more precise picture of the complicated processes involved with our sense of hearing,” says Elias A. Zerhouni, M.D., director of the NIH. “With roughly 15 percent of American adults reporting some degree of hearing loss, it is increasingly vital that we continue making inroads into our understanding of these processes, helping us seek new and better treatments, and opening the doors to better hearing health for Americans.” Researchers have long known that hair cells, small sensory cells in the inner ear, convert sound energy into electrical signals that travel to the brain, a process called mechanotransduction. However, the closer one zooms in on the structures involved, the murkier our understanding becomes. When fluid in the inner ear is set into motion by vibrations emanating from the bones of the middle ear, the rippling effect causes bristly structures atop the hair cells to bump up against an overlying membrane and to deflect.

ST. LOUIS – Researchers at Saint Louis University School of Medicine have received nearly half a million dollars from the National Eye Institute to study a protein thought to be linked to Alzheimer’s disease and its possible relationship to age-related macular degeneration, the leading cause of blindness in people over 60. Apolipoprotein E (apoE) is a protein component that helps transport cholesterol in the blood between the liver and other tissues, says Steven Fliesler, Ph.D., professor and director of research in the department of ophthalmology at Saint Louis University School of Medicine and lead investigator. It also is present in the brain and other nervous tissues, including the retina. There are three genetically determined forms of apoE (apoE-2, apoE-3 and apoE-4), each encoded by a specific sequence of DNA . Studies suggest that apoE-3 may play a protective role in the nervous system, assisting in the repair of nervous tissue, such as after a brain injury. On the other hand, people who have elevated levels of the apoE-4 version of the protein are at an increased risk for developing the late onset, familial type of Alzheimer’s disease. The mystery SLU researchers are now trying to solve is why the reverse seems to be true when it comes to advanced macular degeneration. © 2003 Saint Louis University

Howard Hughes Medical Institute researchers have found that mutations in a single structural protein can determine whether an insect develops the highly organized, light-harvesting eye that flies have, or the optically simpler compound eye of a beetle or bee. In their experiments, the scientists showed that flies without this structural protein develop a more primitive eye. This outcome was reversed in the laboratory when researchers supplied the missing protein to a more primitive eye system, inducing it to “evolve” into the more advanced eye. “It’s not unusual to see alterations in regulatory proteins with a profound effect on form and function. This new finding, however, is unique because it illustrates how a change in a single structural protein can lead to such a spectacular change in form and function.” Charles S. Zuker These findings “help illustrate the beauty and power of evolution — how small changes can have such an incredible impact,” said HHMI investigator Charles S. Zuker, who led the study. Zuker and his colleagues at the University of California, San Diego reported their findings October 1, 2006, in an advance online publication in the journal Nature. The lead author of the paper was Andrew Zelhof. Robert Hardy and Ann Becker were co-authors. © 2006 Howard Hughes Medical Institute.

By BENEDICT CAREY Staring at a pattern meant to evoke an optical illusion is usually an act of idle curiosity, akin to palm reading or astrology. The dot disappears, or it doesn’t. The silhouette of the dancer spins clockwise or counterclockwise. The three-dimensional face materializes or not, and the explanation always seems to have something to do with the eye or creativity or even personality. The radiating lines trick the brain into perceiving motion forward, so the center appears to bulge. That’s the usual cue to nod and feign renewed absorption in the pattern. In fact, scientists have investigated such illusions for hundreds of years, looking for clues to how the brain constructs a seamless whole from the bouncing kaleidoscope of light coming through the eyes. Brain researchers today call the illusions perceptual, not optical, because the entire visual system is involved, and their theories about what is occurring can sound as exotic as anyone’s. In the current issue of the journal Cognitive Science, researchers at the California Institute of Technology and the University of Sussex argue that the brain’s adaptive ability to see into the near future creates many common illusions. “It takes time for the brain to process visual information, so it has to anticipate the future to perceive the present,” said Mark Changizi, the lead author of the paper, who is now at Rensselaer Polytechnic Institute. “One common functional mechanism can explain many of these seemingly unrelated illusions.” His co-authors were Andrew Hsieh, Romi Nijhawan, Ryota Kanai and Shinsuke Shimojo. Copyright 2008 The New York Times Company

By NATALIE ANGIER For the bubbleheaded young Narcissus of myth, the mirror spun a fatal fantasy, and the beautiful boy chose to die by the side of a reflecting pond rather than leave his “beloved” behind. For the aging narcissist of Shakespeare’s 62nd sonnet, the mirror delivered a much-needed whack to his vanity, the sight of a face “beated and chopp’d with tann’d antiquity” underscoring the limits of self-love. Whether made of highly polished metal or of glass with a coating of metal on the back, mirrors have fascinated people for millennia: ancient Egyptians were often depicted holding hand mirrors. With their capacity to reflect back nearly all incident light upon them and so recapitulate the scene they face, mirrors are like pieces of dreams, their images hyper-real and profoundly fake. Mirrors reveal truths you may not want to see. Give them a little smoke and a house to call their own, and mirrors will tell you nothing but lies. To scientists, the simultaneous simplicity and complexity of mirrors make them powerful tools for exploring questions about perception and cognition in humans and other neuronally gifted species, and how the brain interprets and acts upon the great tides of sensory information from the external world. They are using mirrors to study how the brain decides what is self and what is other, how it judges distances and trajectories of objects, and how it reconstructs the richly three-dimensional quality of the outside world from what is essentially a two-dimensional snapshot taken by the retina’s flat sheet of receptor cells. They are applying mirrors in medicine, to create reflected images of patients’ limbs or other body parts and thus trick the brain into healing itself. Mirror therapy has been successful in treating disorders like phantom limb syndrome, chronic pain and post-stroke paralysis. Copyright 2008 The New York Times Company

The four-eyed spookfish may have seemed strange enough. Now researchers say it doesn't really have four eyes. Instead, it is the first known vertebrate to use mirrors, rather than lenses, to focus light in its eyes. “In nearly 500 million years of vertebrate evolution, and many thousands of vertebrate species living and dead, this is the only one known to have solved the fundamental optical problem faced by all eyes — how to make an image — using a mirror," said Julian Partridge from the University of Bristol. While the spookfish looks like it has four eyes, in fact it has only two, each of which is split into two connected parts. One half points upwards, giving the spookfish a view of the ocean — and potential food — above. The other half, which looks like a bump on the side of the fish's head, points down. These diverticular eyes, as they are called, are unique among all vertebrates in that they use mirrors to make the image, Partridge and colleagues found. Story continues below ↓advertisement | your ad here Very little light penetrates the ocean's waters below a depth of about a half-mile (1 kilometer). Like many other deep-sea fish, the spookfish is adapted to make the most of what little light there is. The spookfish largely looks for flashes of bioluminescent light from other animals. The diverticular eyes image these flashes, warning the spookfish of other animals that are active, and otherwise unseen, below its vulnerable belly. © 2009 LiveScience.com.

The dissociation in the visual system between two separate functions – one that enables us to identify objects and the other to interact with them – has been clearly demonstrated for the first time in healthy humans by researchers at the Hebrew University of Jerusalem. These separate vision-related actions have been documented from the beginning of the 20th century in patients who suffered damage to the visual system as a result of illness or injuries in which one or the other function – identification or action – was damaged. For example, persons suffering from ataxia are able to verbally identify an object presented to them but have difficulty in grasping it, while those who have agnosia can grasp an object if handed to them but are unable to name or indicate the position, size or texture of the object. This dissociation between action and perception suggests the existence of two separate visual streams However, despite the wide research triggered by this theoretical concept, it had not been proved in subjects in whom both streams are functioning normally.

A light-sensitive material developed in space could be used to restore the sight of people with damaged retinas. According to Alex Ignatiev, director of the Space Vacuum Epitaxy Center (SVEC) at the University of Houston, US, tests show that the ceramic photodetector will be compatible with the human eye, unlike earlier prototypes that were based on silicon. Human trials of the device are set to begin later this year. Rod and cone cells in the retina of the human eye send electrical signals to the brain when they detect light. Certain diseases damage these cells and cause blindness, but do not affect the ‘wiring’ – which means that sight could be restored by implanting suitable artificial cells. Now a photodetector developed at SVEC, which is sponsored by NASA, could fit the bill. The device consists of a thin film of lanthanum-doped lead zirconium titanate (PLZT). The material is grown layer by layer – or ‘epitaxially’ – using a process perfected during research under ultra-high-vacuum conditions in the Wake Shield Facility, a small space-based laboratory launched by the space shuttle into low-Earth orbit. The method produces a uniform crystal structure with optimum optical properties. Copyright © IOP Publishing Ltd 1996-2002. All rights reserved.

by Andy Smith a.t.smith@rhul.ac.uk Wade A. R et al. (2002). Functional measurements of human ventral occipital cortex: retinotopy and colour. Phil. Trans. R. Soc. Lond. B., 357:963-973. During the recent boom in functional MRI, vision research has led the way in terms of detailed, quantitative analysis. The main focus of cognitive MRI research has been to identify ‘blobs’ that show significant activity in given cognitive circumstances. This is an essential first step, but does not address the nature of the processing that occurs in the areas so identified. In contrast, vision researchers knew already where to look (at the very back of the brain), and have been mapping the surface of the visual cortex, almost millimetre by millimetre, addressing issues of functional organisation on a much finer scale. This methodological lead has been made possible by the pre-existence of copious physiological and anatomical information about the visual system of other primates. Because of this lead, at a recent Royal Society meeting in London on ‘the physiology of cognitive processes’ the presentations on vision were among the most eagerly received. One of these, presented by Wandell and now published along with the other contributions, illustrates just how far into the visual cortex the fine-scale approach can be taken. © Elsevier Science Limited 2002

Kerri Smith Scientists have developed a way of ‘decoding’ someone’s brain activity to determine what they are looking at. “The problem is analogous to the classic ‘pick a card, any card’ magic trick,” says Jack Gallant, a neuroscientist at the University of California in Berkeley, who led the study. But while a magician uses a ploy to pretend to ‘read the mind’ of the subject staring at a card, now researchers can do it for real using brain-scanning instruments. “When the deck of cards, or photographs, has about 120 images, we can do better than 90% correct,” says Gallant. The technique is a step towards being able to see the contents of someone’s visual experiences. “You can imagine using this for dream analysis, or psychotherapy,” says Gallant. Already the results are helping to provide neuroscientists with a more accurate model of how the human visual system works. If the work can be broadened to developing more general models of how the brain responds to things beyond visual stimuli, such brain scans could help to diagnose disease or monitor the effects of therapy. © 2008 Nature Publishing Group

By CAMILLE SWEENEY These are among the first things to become harder to read as people slide further into middle age and their eyes lose their ability to focus. What can begin as a gentle blur might end with not being able to make out the peas on your plate. This condition, known as presbyopia, is the slow deterioration of close vision and is most commonly attributed to aging. It is caused by a loss of elasticity of the crystalline lens, the structure behind the iris that enables the eye to focus on objects at various distances. The arrival of presbyopia can be “one of those ‘Whoa, I’m aging’ moments,” said Randy Savin, 50, president of an insurance agency in Solon, Ohio. For Mr. Savin, that moment came two years ago when he realized he had to hold the newspaper at a distance to read it. At the time, he could count on both hands the number of prescription glasses he used for distance: he had eight pairs that floated between his two cars, home and office. “I just couldn’t handle the thought of adding readers to my life,” Mr. Savin said. Until recently, there wasn’t much more one could do than to succumb to a pair of reading glasses, or try to correct the problem with either monovision contact lenses (one eye is corrected for distance, one for up close) or laser surgery. Copyright 2009 The New York Times Company

By Tina Hesman Saey Two male squirrel monkeys now see the world in a whole new way — in full color. Female squirrel monkeys can see in color, but male squirrel monkeys are normally red-green colorblind because they lack pigments in the retina that detect those wavelengths of light. Now, researchers have performed gene therapy that allowed two male squirrel monkeys named Sam and Dalton to produce proteins that detect red light. As soon as the red-light-harvesting protein was made in the monkeys’ eyes, the animals were able to discriminate between red and green spots in color vision tests, Jay Neitz of the University of Washington in Seattle and his collaborators report online September 17 in Nature. The experiment wasn’t supposed to work, Neitz says. People born with cataracts don’t develop nerve connections that help the brain make sense of messages sent by the eye. If the defect isn’t corrected early, these people remain essentially blind even if their eyes return to full function later. Because there was no reason to assume color vision was different from other types of vision, the team had assumed it would not be possible to reverse the deficit in an adult animal. Neitz polled experts in the vision field on whether they thought producing photoreceptors in colorblind adult monkeys could give color vision. “Every single person said, ‘absolutely not.’” But the researchers decided to move forward with the experiment to see if they could get the pigment protein to be made in the eye. © Society for Science & the Public 2000 - 2009

DAVID ADAM If you never forget a face, you probably carry a ghostly, bland picture of Mr or Mrs Average in your mind's eye, new research suggests. This image helps you to recognize a long-lost friend with a big nose, for example, because their most striking feature is very different to the one on the face stored in your head. But live among big-nosed people for years, and your imaginary model could change - so that you unwittingly ignore your friend in the street. 1.Leopold, D. A., O'Toole, A. J., Vetter, T. & Blanz, V. Prototype-referenced shape encoding revealed by high-level aftereffects. Nature Neuroscience 4, 89–94 (2001). © Macmillan Magazines Ltd 2000 - NATURE NEWS SERVICE Nature © Macmillan Publishers Ltd 2000 Reg. No. 785998 England.

Expressions of individuality JOHN WHITFIELD You catch a glimpse of someone you think you know, but who you haven't seen for years. You're not sure it's them, then something - a raise of the eyebrow, a toss of the head - gives them away. Without any other information, we can recognize and sex individuals from how they move their heads and faces, researchers now report1. The finding could improve face-recognition security and help to humanize animated 'synthespians'. 1.Hill, H. & Johnston, A. Categorizing sex and identity from the biological motion of faces. Current Biology 11, 880–885 (2001). Nature © Macmillan Publishers Ltd 2001 Reg. No. 785998 England.

Neuroscientists at Jefferson Medical College have clarified how the human eye uses light to regulate melatonin production, and in turn, the body's biological clock. They have discovered what appears to be a fifth human "photoreceptor," and which is the main one to regulate the biological – and non-visual – effects of light on the body. They have identified a novel photopigment in the human eye responsible for reacting to light and controlling the production of melatonin, which plays an important role in the body's circadian rhythms. They also discovered that wavelengths of light in the blue region of the visible spectrum are the most effective in controlling melatonin production. ©2001 Thomas Jefferson University Hospital

Stem cell research is vital to finding cures for blinding diseases
BOSTON - Stem cell research, which holds promise for treatments of a wide variety of diseases, is just as promising for curing some forms of blindness, vision scientists say. In diseases of both the retina – the back of the eye – and the cornea – the front of the eye – stem cells derived from adult or postnatal animals show remarkable ability to replace damaged cells that may be the cause of visual impairment.

The ability to recognize objects in the real world is handled by different parts of the brain than those that allow us to imagine what the world is like. That is the result of a brain mapping experiment published in the March 28 issue of the journal Neuron. The study focused on two cognitive tasks widely used by experimental psychologists. One is mental rotation – mentally rotating a complex object into a different position to compare it with a second similar shape – and object recognition – determining whether two complex objects are the same or different. “Mental rotation and object recognition are indistinguishable from a behavioral viewpoint: You can’t tell them apart,” says the paper’s first author, Isabel Gauthier, assistant professor of psychology at Vanderbilt. “As a result, the field has been deadlocked over the question of whether the brain uses the same mechanism or different mechanisms for the two tasks.”

UH Research Suggests Possible Therapies for Eye Disorders, Injury HOUSTON, – A new study designed to find out why cells in the eye die when exposed to lead may provide novel therapies for retinal damage caused by injury or diseases such as diabetes and retinitis pigmentosa. The study, published in the Feb. 4 issue of the Proceedings of the National Academy of Sciences, focused on identifying how low-level lead exposure during development in mice injures and eventually kills rod-shaped photoreceptor cells, or rods, in the eye. Rods are cells in the eye that help humans see in dim light. The other type of photoreceptors, or light-gathering cells, called cones are responsible for color and spatial vision. Cones are used primarily in daylight and for activities such as reading.

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