Cognitive Biometrics: A Very Personal Login

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Posted on 30th April 2012 by Pacific ClearVision Institute in Retina

Retina and iris scans, fingerprint and palm logins rely on possession of unique anatomical characteristics that you cannot forget as you might a password. But, Kenneth Revett of the British University in Egypt, in El-Sherouk City, reviews the state of the art in an alternative approach to user authentication in the inaugural issue of the International Journal of Cognitive Biometrics.

“Cognitive biometrics is a novel approach to user authentication and/or identification that utilises the response(s) of nervous tissue,” explains Revett, who is the journal’s academic editor. He explains that cognitive biometrics relies on the response of the subject when they are presented with a particular stimulus such as a familiar photograph, a song, a puzzle, or even a Rorschach ink blot.

The response can be acquired through a variety of techniques, including: electroencephalogram (EEG), an electrocardiogram (ECG), electrodermal response (EDR), blood pulse volume (BVP). Other techniques such as near-infrared spectroscopy (NIR), electromyogram (EMG), eye trackers (pupilometry), hemoencephalography (HEG), and related technologies might also be used. The validation of the user is then based on the matching of their response to the stimulus with a pre-recorded ECG, EEG or other metric. The stimuli are designed to elicit responses that are sensitive to the individual’s genetic predispositions, modulated by subjective experiences.

Revett points out that cognitive biometrics can “provide a more intuitive and arguably a more robust and user-friendly authentication protocol that is suitable for both static and continuous authentication requirements,” he says. It might also be combined with other related biometric techniques such as keystroke and/or mouse dynamics, which would increase the level of security to virtually any desired level. He adds that the inaugural issue of the journal not only introduces the concept of cognitive biometrics in more detail than ever before but also presents several papers that focus on a wide variety of issues, such as security and user adoption, associated with implementing cognitive biometrics. The range of papers focuses on factors such as how easy the data is to acquire, persistence, ease of generalisation and deployment issues, Revett adds.

“Provided the proper stimuli are presented, the stimulus-response paradigm provides a powerful methodology for evaluating the authenticity of the subject requesting authentication,” he concludes.

Women Have Bigger Pupils Than Men

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Posted on 30th April 2012 by Pacific ClearVision Institute in General

From an anatomical point of view, a normal, non-pathological eye is known as an emmetropic eye, and has been studied very little until now in comparison with myopic and hypermetropic eyes. The results show that healthy emmetropic women have a wider pupil diameter than men.

Normal, non-pathological emmetropic eyes are the most common type amongst the population (43.2%), with a percentage that swings between 60.6% in children from three to eight years and 29% in those older than 66.

Therefore, a study determines their anatomical pattern so that they serve as a model for comparison with eyes that have refractive defects (myopia, hypermetropia and stigmatism) pathological eyes (such as those that have cataracts).

“We know very little about emmetropic eyes even though they should be used for comparisons with myopic and hypermetropic eyes” Juan Alberto Sanchis-Gimeno, researcher at the University of Valencia and lead author of the study explained.

The project, published in the journal ‘Surgical and Radiologic Anatomy’ shows the values by gender for the central corneal thickness, minimum total corneal thickness, white to white distance and pupil diameter in a sample of 379 emmetropic subjects.

“It is the first study that analyses these anatomical indexes in a large sample of healthy emmetropic subjects” Sanchis-Gimeno states. In recent years new technologies have been developed, such as corneal elevation topography, which allows us to increase our understanding of in vivo ocular anatomy.

Although the research states that there are no big differences between most of the parameters analysed, healthy emmetropic women have a wider pupil diameter than men.

“It will be necessary to investigate as to whether there are differences in the anatomical indexes studied between emmetropic, myopic and hypermetropic eyes, and between populations of different ethnic origin” the researcher concludes.

How the human eye works

Light penetrates through the pupil, crosses the crystalline lens and is projected onto the retina, where the photoreceptor cells turn it into nerve impulses, and it is transferred through the optic nerve to the brain. Rays of light should refract so that they can penetrate the eye and can be focused on the retina. Most of the refraction occurs in the cornea, which has a fixed curvature.

The pupil is a dilatable and contractile opening that regulates the amount of light that reaches the retina. The size of the pupil is controlled by two muscles: the pupillary sphincter, which closes it, and the pupillary dilator, which opens it. Its diameter is between 3 and 4.5 millimetres in the human eye, although in the dark it could reach up to between 5 and 9 millimetres.

Accelerated Corneal Crosslinking Procedure Receives CE Approval; Designed to Strengthen Eye Surface After LASIK

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Posted on 4th April 2012 by Pacific ClearVision Institute in General |LASIK

A procedure called Lasik Xtra, which is designed to strengthen the cornea after LASIK, has received CE approval for marketing in the European Union. It was just approved in Canada as well.

Marketed by Avedro, Inc., Lasik Xtra is a corneal crosslinking procedure that applies the company’s VibeX riboflavin ophthalmic solution to the eye’s surface (cornea), and then uses Avedro’s KXL System to irradiate the cornea with UV-A rays. Lasik Xtra is an accelerated form of crosslinking — Avedro says it takes two minutes — which makes it more convenient to combine with LASIK.

Avedro said that in April it will report on studies that show the procedure has helped people who received hyperopic LASIK, which tends to regress more than myopic LASIK, to maintain the vision correction they had received from LASIK.

Although corneal crosslinking has not received FDA approval yet, Avedro’s VibeX solution has received orphan drug approvals from the agency. Orphan drug status is usually conferred on treatments for rare medical conditions (in this case, keratoconus, which is a gradual thinning of the cornea).

Scientists Produce Eye Structures from Human Blood-Derived Stem Cells

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Posted on 4th April 2012 by Pacific ClearVision Institute in General

For the first time, scientists at the University of Wisconsin-Madison have made early retina structures containing proliferating neuroretinal progenitor cells using induced pluripotent stem (iPS) cells derived from human blood.

And in another advance, the retina structures showed the capacity to form layers of cells – as the retina does in normal human development – and these cells possessed the machinery that could allow them to communicate information. (Light-sensitive photoreceptor cells in the retina along the back wall of the eye produce impulses that are ultimately transmitted through the optic nerve and then to the brain, allowing you to see.) Put together, these findings suggest that it is possible to assemble human retinal cells into more complex retinal tissues, all starting from a routine patient blood sample.

Many applications of laboratory-built human retinal tissues can be envisioned, including using them to test drugs and study degenerative diseases of the retina such as retinitis pigmentosa, a prominent cause of blindness in children and young adults. One day, it may also be possible replace multiple layers of the retina in order to help patients with more widespread retinal damage.

“We don’t know how far this technology will take us, but the fact that we are able to grow a rudimentary retina structure from a patient’s blood cells is encouraging, not only because it confirms our earlier work using human skin cells, but also because blood as a starting source is convenient to obtain,” says Dr. David Gamm, pediatric ophthalmologist and senior author of the study. “This is a solid step forward.”

In 2011, the Gamm lab at the UW Waisman Center created structures from the most primitive stage of retinal development using embryonic stem cells and stem cells derived from human skin. While those structures generated the major types of retinal cells, including photoreceptors, they lacked the organization found in more mature retina.

This time, the team, led by Gamm, Assistant Professor of Ophthalmology and Visual Sciences in the UW School of Medicine and Public Health, and postdoctoral researcher and lead author Dr. Joseph Phillips, used their method to grow retina-like tissue from iPS cells derived from human blood gathered via standard blood draw techniques.

In their study, about 16 percent of the initial retinal structures developed distinct layers. The outermost layer primarily contained photoreceptors, whereas the middle and inner layers harbored intermediary retinal neurons and ganglion cells, respectively. This particular arrangement of cells is reminiscent of what is found in the back of the eye. Further, work by Dr. Phillips showed that these retinal cells were capable of making synapses, a prerequisite for them to communicate with one another.

The iPS cells used in the study were generated through collaboration with Cellular Dynamics International (CDI) of Madison, Wis., who pioneered the technique to convert blood cells into iPS cells. CDI scientists extracted a type of blood cell called a T-lymphocyte from the donor sample, and reprogrammed the cells into iPS cells. CDI was founded by UW stem cell pioneer Dr. James Thomson.

“We were fortunate that CDI shared an interest in our work. Combining our lab’s expertise with that of CDI was critical to the success of this study,” added Dr. Gamm.

Other members of the research team include:

– Kyle Wallace, Amelia Verhoeven, Jessica Martin, Lynda Wright, Wei Shen, Elizabeth Capowski and Enio Perez, of the Waisman Center.
– Sarah Dickerson and Michael Miller of CDI.
– E. Ferda Percen of the Faculty of Medicine, Gazi University, Ankara, Turkey.
– Xiufeng Zhong and Maria Canto-Soler, of the Wilmer Eye Institute at Johns Hopkins Univerity.

The research is supported by the Foundation Fighting Blindness, the National Institutes of Health, the Retina Research Foundation, the UW Institute for Clinical and Translational Research, the UW Eye Research Institute and the E. Matilda Ziegler Foundation for the Blind, Inc.

Eye Health Is Related to Brain Health

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Posted on 4th April 2012 by Pacific ClearVision Institute in General |Retina

People with mild vascular disease that causes damage to the retina in the eye are more likely to have problems with thinking and memory skills because they may also have vascular disease in the brain, according to a study published in the March 14, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.

Damage to the retina is called retinopathy. In the study, the damage was mild enough to not cause significant symptoms.

“Problems with the tiny blood vessels in the eye may be a sign that there are also problems with the blood vessels in the brain that can lead to cognitive problems,” said study author Mary Haan, DrPH, MPH, of the University of California, San Francisco. “This could be very useful if a simple eye screening could give us an early indication that people might be at risk of problems with their brain health and functioning.”

The study involved 511 women with an average age of 69. The women took tests of their thinking and memory skills every year for up to 10 years. Their eye health was tested about four years into the study and scans were taken of their brains about eight years into the study.

A total of 39 women, or 7.6 percent, had retinopathy. The women with retinopathy on average had lower scores on the cognitive tests than the women who did not have retinopathy. The women with retinopathy also had more areas of small vascular damage within the brain, with 47 percent larger volumes of areas of damage than women who did not have retinopathy. In the parietal lobe of the brain, the women with retinopathy had 68 percent larger volumes of areas of damage.

The results remained the same even after adjusting for high blood pressure and diabetes, which can be a factor in vascular issues in the eye and the brain.

On a test of visual acuity, the women with retinopathy had similar scores as the women without the disease.

The study was supported by the National Heart, Lung and Blood Institute, the U.S. Department of Health and Human Services, Wyeth Pharmaceuticals and the National Institute on Aging.

Seeing Movement: Why the World in Our Head Stays Still When We Move Our Eyes

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Posted on 4th April 2012 by Pacific ClearVision Institute in General

When observing a fly buzzing around the room, we should have the impression that it is not the fly, but rather the space that lies behind it that is moving. After all, the fly is always fixed in our central point of view. But how does the brain convey the impression of a fly in motion in a motionless field? With the help of functional magnetic resonance imaging (fMRI) scientists from the Werner Reichardt Centre for Integrative Neuroscience and the Max Planck Institute for Biological Cybernetics in Tübingen have identified two areas of the brain that compare the movements of the eye with the visual movements cast onto the retina so as to correctly perceive objects in motion.

The two areas of the brain that are particularly good at reacting to external movements, even during eye movements, are known as V3A and V6. They are located in the upper half in the posterior part of the brain. Area V3A shows a high degree of integration: it reacts to movements around us regardless of whether or not we follow the moving object with our eyes. But the area does not react to visual movements on the retina when eye movements produce them. Area V6 has similar characteristics. In addition, it can perform these functions when we are moving forwards. The calculations the brain has to perform are more complicated in this case: the three-dimensional, expanding forward movement is superimposed onto the two-dimensional lateral movements that are caused by eye movements.

The scientists Elvira Fischer and Andreas Bartels from the Werner Reichardt Centre for Integrative Neuroscience and the Max Planck Institute for Biological Cybernetics have investigated these areas with the help of functional magnetic resonance imaging (fMRI). fMRI is a procedure that can measure brain activity based on local changes in blood flow and oxygen consumption. Participants in the study were shown various visual scenarios whilst undergoing fMRI scanning. For example, they had to follow a small dot with their eyes while it moved across a screen from one side to the other. The patterned background was either stationary or moved at varying speeds, sometimes slower, faster or at the same speed as the dot. Sometimes the dot was stationary while only the background moved. In a total of six experiments the scientists measured brain activity in more than a dozen different scenarios. From this they have been able to discover that V3A and V6, unlike other visual areas in the brain, have a pronounced ability to compare eye movements with the visual signals on the retina. “I am especially fascinated by V3A because it reacts so strongly and selectively to movements in our surroundings. It sounds trivial, but it is an astonishing capability of the brain,” explains Andreas Bartels, project leader of the study.

Whether it is ourselves who move or something else in our surroundings is a problem about which we seldom think, since at the subconscious level our brain constantly calculates and corrects our visual impression. Indeed, patients who have lost this ability to integrate movements in their surroundings with their eye movements can no longer recognize what it is that ultimately is moving: the surroundings or themselves. Every time they move their eyes these patients feel dizzy. Studies such as this bring us one step closer to an understanding of the causes of such illnesses.

The study was a collaboration between the Werner Reichardt Centre for Integrative Neuroscience and the department for Human Perception, Cognition and Action of Heinrich Bülthoff as well as the department for Physiology of Cognitive Processes of Nikos Logothetis at the Max Planck Institute for Biological Cybernetics.

‘Positive Stress’ Helps Protect Eye from Glaucoma

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Posted on 4th April 2012 by Pacific ClearVision Institute in General |Retina

Working in mice, scientists at Washington University School of Medicine in St. Louis have devised a treatment that prevents the optic nerve injury that occurs in glaucoma, a neurodegenerative disease that is a leading cause of blindness.

Researchers increased the resistance of optic nerve cells to damage by repeatedly exposing the mice to low levels of oxygen similar to those found at high altitudes. The stress of the intermittent low-oxygen environment induces a protective response called tolerance that makes nerve cells — including those in the eye — less vulnerable to harm.

The study, published online in Molecular Medicine, is the first to show that tolerance induced by preconditioning can protect against a neurodegenerative disease.

Stress is typically thought of as a negative phenomenon, but senior author Jeffrey M. Gidday, PhD, associate professor of neurological surgery and ophthalmology, and others have previously shown that the right kinds of stress, such as exercise and low-oxygen environments, can precondition cells and induce changes that make them more resistant to injury and disease.

Scientists previously thought tolerance in the central nervous system only lasted for a few days. But last year Gidday developed a preconditioning protocol that extended the effects of tolerance from days to months. By exposing mice to hypoxia, or low oxygen concentrations, several times over a two-week period, Gidday and colleagues triggered an extended period of tolerance. After preconditioning ended, the brain was protected from stroke damage for at least 8 weeks.

“Once we discovered tolerance could be extended, we wondered whether this protracted period of injury resistance could also protect against the slow, progressive loss of neurons that characterizes neurodegenerative diseases,” Gidday says.

To find out, Gidday turned to an animal model of glaucoma, a condition linked to increases in the pressure of the fluid that fills the eye. The only treatments for glaucoma are drugs that reduce this pressure; there are no therapies designed to protect the retina and optic nerves from harm.

Scientists classify glaucoma as a neurodegenerative disease based on how slowly and progressively it kills retinal ganglion cells. The bodies of these cells are located in the retina of the eye; their branches or axons come together in bundles and form the optic nerves. Scientists don’t know if damage begins in the bodies or axons of the cells, but as more and more retinal ganglion cells die, patients experience peripheral vision loss and eventually become blind.

For the new study, Yanli Zhu, MD, research instructor in neurosurgery, induced glaucoma in mice by tying off vessels that normally allow fluid to drain from the eye. This causes pressure in the eye to increase. Zhu then assessed how many cell bodies and axons of retinal ganglion cells were intact after three or 10 weeks.

The investigators found that normal mice lost an average of 30 percent of their retinal ganglion cell bodies after 10 weeks of glaucoma. But mice that received the preconditioning before glaucoma-inducing surgery lost only 3 percent of retinal ganglion cell bodies.

“We also showed that preconditioned mice lost significantly fewer retinal ganglion cell axons,” Zhu says.

Gidday is currently investigating which genes are activated or repressed by preconditioning. He hopes to identify the changes in gene activity that make cells resistant to damage.

“Previous research has shown that there are literally hundreds of survival genes built into our DNA that are normally inactive,” Gidday says. “When these genes are activated, the proteins they encode can make cells much less vulnerable to a variety of injuries.”

Identifying specific survival genes should help scientists develop drugs that can activate them, according to Gidday.

Neurologists are currently conducting clinical trials to see if stress-induced tolerance can reduce brain damage after acute injuries like stroke, subarachnoid hemorrhage or trauma.

Gidday hopes his new finding will promote studies of tolerance’s potential usefulness in animal models of Parkinson’s disease, Alzheimer’s disease and other neurodegenerative conditions.

“Neurons in the central nervous system appear to be hard-wired for survival,” Gidday says. “This is one of the first steps in establishing a framework for how we can take advantage of that metaphorical wiring and use positive stress to help treat a variety of neurological diseases.”