Posts tagged vision
Articles and news from the latest research reports.
Pupil Dilation Reveals Sexual Orientation
There is a popular belief that sexual orientation can be revealed by pupil dilation to attractive people, yet until now there was no scientific evidence. For the first time, researchers at Cornell University used a specialized infrared lens to measure pupillary changes to participants watching erotic videos. Pupils were highly telling: they widened most to videos of people who participants found attractive, thereby revealing where they were on the sexual spectrum from heterosexual to homosexual.
The findings were published August 3 in the scientific journal PLoS ONE.
Implantable Telescope Technology
Implantable Miniature Telescope along with the cornea, enlarges images in front of the eye approximately 2.2 or 2.7 times their normal size (depending on the model used). The magnification allows central images to be projected onto healthy perimacular areas of the retina instead of the macula alone, where breakdown of photoreceptors and loss of vision has occurred. This helps reduce the ‘blind spot’ and allows the patient to distinguish and discern images that may have been unrecognizable or difficult to see.
The telescope is about the size of a pea (3.6 mm diameter; 4.4 mm length) and is surgically placed inside the eye.
Eyes and Attention of Men and Women Meander in Distinctly Different Ways
Dr. Itti’s lab studied 34 participants as they watched videos of people being interviewed. Behind the interview subjects, within the video frame, pedestrians, bicycles and cars passed by — distractions included to pull attention away from the filmed conversation.
While participants watched and listened to the interview, another camera was pointed at participants’ eyes, recording the movement of their pupils as they glanced across the screen.
Researchers discovered the following:
• Men, when focused on the person being interviewed, parked their eyes on the speaker’s mouth. They tended to be most distracted by distinctive movement behind the interview subjects.
• By contrast, women shift their focus between the interview subject’s eyes and body. When they were distracted, it was typically by other people entering the video frame.
The longer you’re awake, the slower you get
July 27, 2012
Anyone that has ever had trouble sleeping can attest to the difficulties at work the following day. Experts recommend eight hours of sleep per night for ideal health and productivity, but what if five to six hours of sleep is your norm? Is your work still negatively affected? A team of researchers at Brigham and Women’s Hospital (BWH) have discovered that regardless of how tired you perceive yourself to be, that lack of sleep can influence the way you perform certain tasks.
This finding is published in the July 26, 2012 online edition of The Journal of Vision.
"Our team decided to look at how sleep might affect complex visual search tasks, because they are common in safety-sensitive activities, such as air-traffic control, baggage screening, and monitoring power plant operations," explained Jeanne F. Duffy, PhD, MBA, senior author on this study and associate neuroscientist at BWH. "These types of jobs involve processes that require repeated, quick memory encoding and retrieval of visual information, in combination with decision making about the information."
Researchers collected and analyzed data from visual search tasks from 12 participants over a one month study. In the first week, all participants were scheduled to sleep 10-12 hours per night to make sure they were well-rested. For the following three weeks, the participants were scheduled to sleep the equivalent of 5.6 hours per night, and also had their sleep times scheduled on a 28-hour cycle, mirroring chronic jet lag. The research team gave the participants computer tests that involved visual search tasks and recorded how quickly the participants could find important information, and also how accurate they were in identifying it. The researchers report that the longer the participants were awake, the more slowly they identified the important information in the test. Additionally, during the biological night time, 12 a.m. -6 a.m., participants (who were unaware of the time throughout the study) also performed the tasks more slowly than they did during the daytime.
"This research provides valuable information for workers, and their employers, who perform these types of visual search tasks during the night shift, because they will do it much more slowly than when they are working during the day," said Duffy. "The longer someone is awake, the more the ability to perform a task, in this case a visual search, is hindered, and this impact of being awake is even stronger at night."
While the accuracy of the participants stayed the fairly constant, they were slower to identify the relevant information as the weeks went on. The self-ratings of sleepiness only got slightly worse during the second and third weeks on the study schedule, yet the data show that they were performing the visual search tasks significantly slower than in the first week. This finding suggests that someone’s perceptions of how tired they are do not always match their performance ability, explains Duffy.
Provided by Brigham and Women’s Hospital
Source: medicalxpress.com
Eye-Writing Technology: Writing in Cursive With Your Eyes Only
A new technology might allow people who have almost completely lost the ability to move their arms or legs to communicate freely, by using their eyes to write in cursive. The eye-writing technology tricks the neuromuscular machinery into doing something that is usually impossible: to voluntarily produce smooth eye movements in arbitrary directions.
The technology relies on changes in contrast to trick the eyes into the perception of motion. When viewing that changing visual display, people can learn to control their eye movements smoothly and at will, the new study shows. It doesn’t take very much practice either.
Chemical Makes Blind Mice See; Compound Holds Promise for Treating Humans
ScienceDaily (July 25, 2012) — A team of University of California, Berkeley, scientists in collaboration with researchers at the University of Munich and University of Washington, in Seattle, has discovered a chemical that temporarily restores some vision to blind mice, and is working on an improved compound that may someday allow people with degenerative blindness to see again.
Mice with a genetic disease that causes blindness regained some sight after injection with a chemical “photoswitch.” The eye of the untreated mouse on the left shows no response to light, while the pupil of the mouse on the right, which was injected with the chemical, contracts in light. (Credit: Image courtesy of University of California - Berkeley)
The approach could eventually help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness, as well as age-related macular degeneration, the most common cause of acquired blindness in the developed world. In both diseases, the light sensitive cells in the retina — the rods and cones — die, leaving the eye without functional photoreceptors.
The chemical, called AAQ, acts by making the remaining, normally “blind” cells in the retina sensitive to light, said lead researcher Richard Kramer, UC Berkeley professor of molecular and cell biology. AAQ is a photoswitch that binds to protein ion channels on the surface of retinal cells. When switched on by light, AAQ alters the flow of ions through the channels and activates these neurons much the way rods and cones are activated by light.
"This is similar to the way local anesthetics work: they embed themselves in ion channels and stick around for a long time, so that you stay numb for a long time," Kramer said. "Our molecule is different in that it’s light sensitive, so you can turn it on and off and turn on or off neural activity."
Because the chemical eventually wears off, it may offer a safer alternative to other experimental approaches for restoring sight, such as gene or stem cell therapies, which permanently change the retina. It is also less invasive than implanting light-sensitive electronic chips in the eye.
"The advantage of this approach is that it is a simple chemical, which means that you can change the dosage, you can use it in combination with other therapies, or you can discontinue the therapy if you don’t like the results. As improved chemicals become available, you could offer them to patients. You can’t do that when you surgically implant a chip or after you genetically modify somebody," Kramer said.
"This is a major advance in the field of vision restoration," said co-author Dr. Russell Van Gelder, an ophthalmologist and chair of the Department of Ophthalmology at the University of Washington, Seattle.
Kramer, Van Gelder, chemist Dirk Trauner and their colleagues at UC Berkeley, the University of Washington, Seattle, and the University of Munich will publish their findings on July 26, in the journal Neuron.
The blind mice in the experiment had genetic mutations that made their rods and cones die within months of birth and inactivated other photopigments in the eye. After injecting very small amounts of AAQ into the eyes of the blind mice, Kramer and his colleagues confirmed that they had restored light sensitivity because the mice’s pupils contracted in bright light, and the mice showed light avoidance, a typical rodent behavior impossible without the animals being able to see some light. Kramer is hoping to conduct more sophisticated vision tests in rodents injected with the next generation of the compound.
"The photoswitch approach offers real hope to patients with retinal degeneration," Van Gelder said. "We still need to show that these compounds are safe and will work in people the way they work in mice, but these results demonstrate that this class of compound restores light sensitivity to retinas blind from genetic disease."
From optogenetics to implanted chips
The current technologies being evaluated for restoring sight to people whose rods and cones have died include injection of stem cells to regenerate the rods and cones; “optogenetics,” that is, gene therapy to insert a photoreceptor gene into blind neurons to make them sensitive to light; and installation of electronic prosthetic devices, such as a small light-sensitive retinal chip with electrodes that stimulate blind neurons. Several dozen people already have retinal implants and have had rudimentary, low vision restored, Kramer said.
Eight years ago, Kramer, Trauner, a former UC Berkeley chemist now at the University of Munich, and their colleagues developed an optogenetic technique to chemically alter potassium ion channels in blind neurons so that a photoswitch could latch on. Potassium channels normally open to turn a cell off, but with the attached photoswitch, they were opened when hit by ultraviolet light and closed when hit by green light, thereby activating and deactivating the neurons.
Subsequently, Trauner synthesized AAQ (acrylamide-azobenzene-quaternary ammonium), a photoswitch that attaches to potassium channels without the need to genetically modify the channel. Tests of this compound are reported in the current Neuron paper.
New versions of AAQ now being tested are better, Kramer said. They activate neurons for days rather than hours using blue-green light of moderate intensity, and these photoswitches naturally deactivate in darkness, so that a second color of light is not needed to switch them off.
"This is what we are really excited about," he said.
Source: Science Daily
New vision therapy for stroke victims
The innovative vision therapy tool will be used to evaluate and train people with a vision deficit caused by a brain injury or dysfunction.
Each year about 220,000 Australians suffer from an acquired brain injury caused by strokes, car accidents and trauma. Of those, about 30 to 35 per cent acquire neurological vision impairments as a result of damage to the brain, not the eyes, causing many patients to only see half an image.
The software, developed by MDPP Research Associate Dr Fabian Lim, will be trialled by NVT Systems as a new therapeutic product for their clients.
The touch screen tool features five visual tasks with varying degrees of difficulty, including a line-tracing exercise and a shopping catalogue task where the object is to match images in the catalogue with a shopping list.
Dr. Lim said the software would give health care providers a “quantitative measure” for assessing vision deficit, tracking improvements and targeting specific impediments, offering a more effective alternative to traditional pen and paper assessments.
“By repeatedly practicing these exercises patients learn how to scan their surroundings and look for things that might not be in their field of view, and ultimately improve their visual sense,” Dr. Lim said.
NVT Systems is now trialling the simulator software with patients from organisations such as Guide Dogs SA.NT.
NVT Systems Manager Training and Research, Mrs Allison Hayes, said the fantastic work by the Medical Device Partnering Program had enabled the company to expand its product range for local and international markets.
“One of the great things about this new tool is that we will be able to measure important parameters that could be used by carers to map improvements in performance and target specific deficits,” Mrs. Hayes said.
“The visual skills taught using the touch screen device can be transferred to functional activities of daily living, helping our clients to carry out important everyday activities in the home and community.”
The authors of the article have added another dimension to this illusion of body ownership. Using virtual reality they have shown that a virtual body with one very long arm can be incorporated into body representation. An arm up to three or possibly even four times the length of a person’s real arm can be felt as if it was the person’s own arm. This is notwithstanding the fact that having one such long arm introduces a gross asymmetry in the body. An extended body space (a body with longer limbs occupies more volume than a normal body) affects also the special space surrounding our body that is called peripersonal space — a space that when violated by objects or other people can be experienced as a threat or intimacy, depending on the context.
In the experiment 50 people experienced virtual reality where they had a virtual body. They put on a head-mounted display so that all around themselves they saw a virtual world. When they looked down towards where their body should be, they saw a virtual body instead of their real one. They had their dominant hand resting on a table with a special textured material that they could feel with their real hand, but also see their virtual hand touching it. So as they moved their real hand over the surface of this table they would see the virtual hand doing the same.
The results of the study were analysed by using a questionnaire to assess the subjective illusion that the virtual arm was part of the person’s body; a pointing task, where the arm that did not grow in length was required to point towards where the other hand was felt to be (with eyes shut), and a response to a threat task, in which a saw fell down towards the virtual hand (figure E, F) and it was measured whether people would move their real hand in an attempt to avoid it.
Based on these data, researchers found that people did have the illusion that the extended hand was their own. Even when the virtual arm was 4 times the length of the corresponding real arm, still 40-50% of participants showed signs of incorporation of the virtual arm as part of their body representation. It was also found that vision alone is a very powerful inducer of the illusion of virtual arm ownership — those who experienced the inconsistent condition where the virtual hand did not touch the table, even though the real hand felt the table top, had a strong illusion of ownership over the virtual arm.
These results show how malleable is our body representation, even incorporating strong asymmetries in the body shape, which do not correspond at all to the average human shape. This type of research will help neuroscientists to understand how the brain represents the body, and ultimately may help people overcome illnesses that are based on body image distortions.
Brain discovery sheds light on link between vision and emotion
Neuroscientists have discovered a new area of the brain that is uniquely specialised for peripheral vision and could be targeted in future treatments for panic disorders and Alzheimer’s disease.
Published today in high impact journal Current Biology, researchers led by Dr Hsin-Hao Yu and Professor Marcello Rosa from Monash University’s Department of Physiology found that a brain area, known as prostriata, was specialised in detecting fast-moving objects in peripheral vision.
This area, located in a primitive part of the cerebral cortex, has characteristics unlike any other visual area described before, including a “direct line” of communication to brain areas controlling emotion and quick reactions.
Dr Yu said the discovery, identified during the development of the Monash Vision Group’s bionic eye, funded through the ARC Research in Bionic Vision Science and Technology Initiative, could lead to new treatments for panic disorders such as agoraphobia (fear of open spaces) and may extend into other medical areas including Alzheimer’s treatment.
“The brain is the most complex organ in the human body and perhaps the most remarkable. These findings change how we think of the brain in terms of how visual information is processed,” Dr Yu said.
“This area is likely to be hyperactive in panic disorder, with agoraphobia. This knowledge could lead to treatment options for the hyperactivity, and therefore sensitivity to such disorders, particularly the fear of open spaces.
“Correlation with previous studies also shows that prostriata is one of the first areas affected in Alzheimer’s disease. This knowledge helps to explain spatial disorientation and the tendency to fall, which are among the earliest signs of a problem associated with Alzheimer’s.”
Professor Rosa said this area had ultra-fast responses to visual stimuli, simultaneously broadcasting information to brain areas that control attention, emotional and motor reactions. This challenges current conceptions of how the brain processes visual information.
“This suggests a specialised brain circuit through which stimuli in peripheral vision can be fast-tracked to command quickly coordinated physical and emotional responses,” Professor Rosa said.
Strobe Eyewear Training Improves Visual Memory
ScienceDaily (July 23, 2012) — Stroboscopic training, performing a physical activity while using eyewear that simulates a strobe-like experience, has been found to increase visual short-term memory retention, and the effects lasted 24 hours.
(Credit: Image courtesy of Duke University)
Participants completed a memory test that required them to note the identity of eight letters of the alphabet that were briefly displayed on a computer screen. After a variable delay, participants were asked to recall one of the eight letters. On easy-level trials, the recall prompt came immediately after the letters disappeared, but on more difficult trials, the prompt came as late as 2.5 seconds following the display. Because participants did not know which letter they would be asked to recall, they had to retain all of the items in memory.
"Humans have a memory buffer in their brain that keeps information alive for a certain short-lived period," said Greg Appelbaum, assistant professor of psychiatry at Duke University and first author of the study. "Wearing the strobe eyewear during the physical training seemed to boost the ability to retain information in this buffer."
The strobe eyewear disrupts vision by only allowing the user to see glimpses of the world. The user must adjust their visual processing in order to perform normally, and this adjustment produces a lingering benefit; once participants removed the strobe eyewear, there was an observed boost in their visual memory retention, which was found to last 24 hours.
Earlier work by Appelbaum and the project’s senior researcher, Stephen Mitroff, had shown that stroboscopic training improves visual perception, including the ability to detect subtle motion cues and the processing of briefly presented visual information. Yet the earlier study had not determined how long the benefits might last.
"Our earlier work on stroboscopic training showed that it can improve perceptual abilities, but we don’t know exactly how," says Mitroff, associate professor of psychology & neuroscience and member of the Duke Institute for Brain Sciences. "This project takes a big step by showing that these improved perceptual abilities are driven, at least in part, by improvements in visual memory."
"Improving human cognition is an important goal with so many benefits," said Appelbaum, also a member of the Duke Institute for Brain Sciences. "Interestingly, our findings demonstrate one way in which visual experience has the capacity to improve cognition."
Source: Science Daily