What we would like you to do is to find a topic from this week's chapter that you were interested in and search the internet for material on that topic. You might, for example, find people who are doing research on the topic, you might find web pages that discuss the topic, you might find a video clip that demonstrates something related to the topic, etc. What you find and use is pretty much up to you at this point. Please be sure to use at least 3 quality resources. If you use videos, please limit it to one video.
Once you have completed your search and explorations we would like you to:
1a) State what your topic is.
1b) Discuss how the topic relates to the chapter.
1c) Discuss why you are interested in it.
2) Next, we would like you to take the information you read or viewed related to your topic, integrate/synthesize it, and then write about the topic in a knowledgeable manner. By integrating/synthesizing we mean taking what your read/experienced from the internet search organize the information into the main themes, issues, info, examples, etc. about your topic and then write about the topic in your own words using the information you have about the topic.
Synthesizing information is hard for some people to do - many students write what we refer to as "serial abstracts." They are tempted to talk about the websites rather than the topic proper Serial abstract writers will talk all about website #1, start a new paragraph and talk all about web site #2, start a new paragraph and talk all about web site #3, and then write some kind of conclusion about the three websites they used. Serial means one after the other...again, this is what you DON'T want to do! We want you to talk about the topic, not the websites!
Also, if all three sites are on the same one topic it will be easier.
At first it is a real challenge to get out of the habit of writing "serial abstracts," but we assure you once you get the hang of it writing about the topic is much easier to do using the integration method. And besides this is the way researchers and scientists write their technical reports and findings - many of you will have to be able to do this for other classes and for jobs that you may eventually be hired for so now is a good time to learn this skill.
At this point don't worry so much about a grade, worry about doing your best to have fun with the topic and then integrate it into your own words to share what you found and what you now know.
3) List the terms you used from the text and from your reference websites.
4) At the end of your post, please include working URLs for the three websites. For each URL you have listed indicate why you chose the site and the extent to which it contributed to your post.
Topic: The Primary Visual Cortex (V1), Area 17, Striate Cortex
The primary visual area (V1) of the cerebral cortex is the first stage of cortical processing of visual information. Area V1 contains a complete map of the visual field covered by the eyes. It receives its main visual input from the lateral geniculate nucleus of the thalamus (LGN), and sends its main output to subsequent cortical visual areas
Did you know that the discovery of primary visual cortex is attributed to Panizza, who published in 1855 his observations on the brains of patients who had become blind after strokes? Panizza confirmed these observations by performing enucleation or cortical lesions in experimental animals. When these results were not noticed, and further experiments were performed independently by three other researchers named Ferrier, Munk, and Schafer. The precise map of the visual field contained in area V1 was discovered in the 1920s in patients with strokes and bullet wounds. I was definitely surprised by this discovery.
Now, the key properties of primary visual cortex were discovered by Hubel and Wiesel through the recording of electrical activity in experimental animals. This started in the 1950s, when they published a seminal series of papers on V1's cellular responses, anatomy, development, and connectivity. It was research/discovery that paved the way for further advancement.
The whole process of bringing together the inputs from what two eyes at the level of the striate cortex provides more than just sight, it is the basis for stereopsis, the special sensation of depth that arises from viewing nearby objects with two eyes instead of one. Because the two eyes look at the world from slightly different angles, objects that lie in front of or behind the plane of fixation project to noncorresponding points on the two retinas.
I found much information when it comes to damaged primary visual cortexs. Damage to primary visual cortex, causes blindness in some portion of visual field. The exact location depends on where the brain damage is. But person can still perceive objects and their backgrounds.
Damage to visual association cortex can produce varying amounts of difficulty in perceiving shapes and objects or in perceiving particular visual characteristics. It can disrupt color vision (achromatopia) normal vision but in black and white--no color.
Damage to another subdivision can make it difficult for a person to perceive movements and keep track of moving objects, sees changes in location, but no sensation of movement. Damage to the visual association cortex in the parietal lobe can make it difficult for a person to keep track of the location of objects in the visual scene (Balint’s syndrome) can recognize an object when they look directly at them but unable to see where they are located. The scene in front of them is a jumble of individual objects, arranged in no particular order.
Damage to visual association cortex of the temporal lobe can disrupt the ability to recognize objects without affecting the ability to see colors, movements, or fine details (visual agnosia). One form of visual agnosia makes it difficult for person to recognize particular faces (prosopagnosia). Most people with prosopagnosia have difficulty recognizing other complex visual stimuli as well.
Going further into research and seeking out information on treatments and/or what they can do depends on what or how much damage there is to the primary visual cortex and or what the damage of different diseases and/or disorders. One study/treatment research I found interesting was done by the NeuroVision Technology Center, which was a noninvasive, patient-specific, perceptual learning program based on visual stimulation and facilitation of neural connections at the cortical level, involving a computerized visual training regimen using Gabor patches, to improve contrast sensitivity and visual acuity. The efficacy of NeuroVision in enhancing uncorrected visual acuity (UCVA) and unaided contrast sensitivity function (CSF) in patients with low myopia or early presbyopia. This was a very specific treatment/study towards myopia or early presbyopia.
It is the hope of many researchers that a careful investigation into the structure and function of the visual pathways using chemical, electrophysiological, genetic, and behavioural approaches will culminate in a true understanding of how the brain provides us with this most crucial of sensory capabilities, VISION.
http://medical-dictionary.thefreedictionary.com/Primary+visual+cortex
http://hubel.med.harvard.edu/book/b23.htm
http://webvision.med.utah.edu/book/part-ix-psychophysics-of-vision/the-primary-visual-cortex/
http://www.ncbi.nlm.nih.gov/books/NBK11112/
Terminology: Primary Visual Area, researchers, function, visual pathways, chemical, electrophysiological, genetic, sensory, vision, cerebral cortex, parietal lobe, sensation, visual association cortex, colors, visual agnosia, prosopagnosia, visual stimuli, Balint’s syndrome, cortical processing, visual, Area V1, eyes, lateral geniculate nucleus, thalamus (LGN), cortical visual areas, patients, blind, Panizza, observations, strokes, enucleation, cortical lesions, experimental, results, experiments, Hubel, Wiesel, electrical activity, cellular responses, anatomy, development, connectivity, Ferrier, Munk, Schafer, retina, color vision, brain damage, myopia, presbyopia, sensitivity function.
The topic I choose to research is Amblyopia. This is also called lazy eye (though one website argued this was the incorrect term which I will explain later) and was discussed in the book. Amblyopia is a condition that causes weakened vision in one eye for various reasons. Whatever the reason it is a failure for one eye to work properly with the brain, and therefore it is slowly weakened.
The most common causes are estropia, extropia, deprivation, and refractive. Strambismic amblyopia, which is the proper term for lazy eye, is actually the turning of the eye which may cause the amblyopia. Estropia refers to the eye pointing in, and extropia refers to the eye pointing out. Deprivation refers to either a cataract or other physical object that is blocking the eye and blurring the vision. Refractive amblyopia is caused by a refractive error in the eye, in other words the eye isn’t relaying light properly or the image, causing weakened vision.
This disorder typically only occurs in children. If adults have it, it is typically because they had it as a child and treatment was not given or effective. There is little research done on treatment of amblyopia in adults, so it is suggested to treat it as soon as it is diagnosed.
Treatment options include eye patches, contacts, glasses, eye drops, and occasionally surgery. Surgery is usually only done if a physical deformity such as a cataract or heavy eyelid is blocking the eye, or if a child has strambismic amblyopia and surgery can straighten the eyes. Atropine is the term for the drops used that blur the vision in the better-seeing eye and force the weakened one to strengthen by being used more. The eye patch has the same effect by blocking the vision in the good eye, and forcing the weaker one to work. The contacts and glasses typically do not work alone. Patching and the eye drops are the most effective.
I was interested in this topic because I like disorders of the human brain and body, and wanted to know more about how this disorder worked. I also remember seeing little kids with patches on their eyes when I was a child, but never really knew why it was that they were wearing them.
Terms Used: amblyopia, refractive, lazy eye, estropia, extropia, deprivation, strambismic, eye patch, atropine
http://www.aapos.org/terms/conditions/21
https://www.nei.nih.gov/health/amblyopia/amblyopia_guide
http://www.strabismus.org/amblyopia_lazy_eye.html
My topic is amblyopia. This topic relates to the chapter because it was moderately discussed towards the end of the chapter. I am interested in it because my brother has the affliction, yet has managed to compensate greatly for it. I would like to learn more about how it happens and what it does exactly.
Amblyopia is a condition where one eye cannot focus or see as well as the other. Often referred to as “lazy eye,” it is the most common cause of poor vision in children. Someone with this condition doesn’t send as many neuro-electrical signals to the brain with the lower functioning eye. Caused by a number of reasons, the under-usage of the neural pathways effectively damages the ability of the eye to see normally. For example, if a natural path in the forest stops being used, it will soon disappear from the forest re-growing over the path. To keep that path, it needs to continue being used. Neural pathways are the same. Because of this, when a pathway is not used during a critical period (this case childhood) the pathway will lose ability to function. So, while amblyopia can be treated, it is essential that it be treated early on, or the neural pathways will not be able to learn to see properly in that particular eye.
Amblyopia comes in three major forms. The first of these is strabismic amblyopia. This occurs when one of the eyes may not be straightly aligned. The eye may turn inwards (esotropia) or turn outwards (exotropia). When this happens, the person’s brain would shut off power to that eye, cutting off that neural pathway. The next possible cause of amblyopia is deprivation amblyopia. This happens when something like a cataract (a clouding of the lens) blocks vision in an eye. With the vision blocked, there are little to no impulses making it through to the neural pathway. The third cause of amblyopia is refractive amblyopia. This happens when there is a discrepancy between how well each eye can see. If one eye has a higher level of astigmatism, farsightedness, or nearsightedness, than the brain will again, switch off the eye with less ability to see. In these causes, corrective glasses or surgery can solve the immediate problem, but that will not fix everything. The eye with problems will have already “learned” to see blurry or no images. It doesn’t know how to see clear images. Therefore, further treatment is necessary.
A very common treatment for amblyopia is an eye patch. Typically, a band-aid type patch is used in lieu of a pirate-esque patch to prevent treatment-damaging peeking. The patch is placed over the dominant eye. This forces the weaker eye to switch back on and re-learn how to see properly. If done in the “critical” period as mentioned before, the neural pathways will still be able to re-form from the new surge of signals. If not treated in time, the pathway will never heal. For less severe cases of amblyopia, special eye drops can be used to temporarily blur vision in the dominant eye. This will then act similar to the patch. The earlier the treatment, the more effective it will be. Neural plasticity tends to drop off entering adolescent years. Some research at the National Institutes of Health state that treatment could still have moderate effect as late as fourteen. However, it still stands that the younger at treatment, the better.
http://www.aapos.org/terms/conditions/21
https://www.youtube.com/watch?v=gGAu1Z0urpA
https://www.nei.nih.gov/health/amblyopia/amblyopia_guide
Terms: Amblyopia; lazy eye; neuro-electrical; neurological pathway; strabismic amblyopia; esotropia; exotropia; deprivation amblyopia; cataract; refraction amblyopia; nearsightedness; farsightedness; astigmatism
My topic is amblyopia. This topic relates to the chapter because it was moderately discussed towards the end of the chapter. It is a disorder in vision due unequal ability to see between the eyes. I am interested in amblyopia mostly because my brother has the affliction. Despite this, he has managed to compensate greatly for it. Until further research, I wasn’t entirely sure how or why this happened to people. I want to understand what my brother goes through. Therefore, I would like to learn more about how it happens and what it does exactly.
Amblyopia is a condition where one eye cannot focus or see as well as the other. Often referred to as “lazy eye,” amblyopia is the most common cause of poor vision in children. For someone with this condition, the weaker eye does not send as nearly as many neurological-electrical signals to the brain. This can be caused by a number of reasons. For one, the under-usage of the neural pathways will effectively damage the ability of the eye to see normally. This is because the usage of those pathways is needed to keep them functioning well. For example, if a natural path in the forest stops being used, it will soon disappear from the forest using the area for other purposes, such as growing plants. To keep that path, the path needs to continue being used. Neural pathways are similar. If a neural pathway is not used for a specific cause, the neurons will be utilized elsewhere. Because of this, when a pathway is not used during a critical period, the pathway will lose ability to function. A critical period is a length of time up until adolescence where the mind is most able to learn and change. So, while amblyopia can be treated, it is essential that it be treated early on. Otherwise, the neural pathways will not be able to learn to see properly in that particular eye. The deficit in visual acuity in that eye will then occur despite the actual problem affecting the eye being fixed, simply because the brain does not know how to process clear images from that eye.
Amblyopia comes in three major forms. The first of these is strabismic amblyopia. Strabismic amblyopia can be caused when one of the eyes is not be straightly aligned. The eye may turn inwards (esotropia) or turn outwards (exotropia). When this happens, the person’s brain would shut off power to that eye, cutting off that neural pathway. The next possible cause of amblyopia is deprivation amblyopia. This happens when something like a cataract (a clouding of the lens) blocks vision in an eye. With the vision blocked, there are little to no impulses making it through to the neural pathway. The third cause of amblyopia is refractive amblyopia. This happens when there is a discrepancy between how well each eye can see. If one eye has a higher level of astigmatism, farsightedness, or nearsightedness, than the brain will again, switch off the eye with less ability to see. In these causes, corrective glasses or surgery can solve the immediate problem, but that will not fix everything. The eye with problems will have already “learned” to see blurry or no images. It doesn’t know how to see clear images. Therefore, further treatment is necessary.
A very common treatment for amblyopia is an eye patch. Typically, a band-aid type patch is used in lieu of a pirate-esque patch to prevent treatment-damaging peeking. The patch is placed over the dominant eye. This forces the weaker eye to switch back on and re-learn how to see properly. If done in the “critical” period as mentioned before, the neural pathways will still be able to re-form from the new surge of signals. If not treated in time, the pathway will never heal. For less severe cases of amblyopia, special eye drops can be used to temporarily blur vision in the dominant eye. This will then act similar to the patch. The earlier the treatment, the more effective it will be. Neural plasticity tends to drop off entering adolescent years. Some research at the National Institutes of Health state that treatment could still have moderate effect as late as fourteen. However, it still stands that the younger at treatment, the better.
https://www.nei.nih.gov/health/amblyopia/amblyopia_guide
I chose this source because it was a very basic collection of information on the subject. After reading this article I had a good foundation for learning more about amblyopia.
http://www.aapos.org/terms/conditions/21
I liked this source because it went further into depth about amblyopia. It had a lot of good information that really allowed me to understand the disorder.
https://www.youtube.com/watch?v=gGAu1Z0urpA
I chose this source because I find that visuals allowed me to learn about things a bit easier. Watching a video about the subject gave me a better, more complete understanding.
Terms: Amblyopia; lazy eye; neuro-electrical; neurological pathway; strabismic amblyopia; esotropia; exotropia; deprivation amblyopia; cataract; refraction amblyopia; nearsightedness; farsightedness; astigmatism
1. A) My topic is amblyopia.
B) This relates to this chapter because it is a problem between the brain and eye working together. It is a problem with vision.
C) I am interested in this topic because my brother actually has a lazy eye. I liked finding out more information about it and learning about different causes and treatment and what it actually is.
2. Amblyopia is also known as lazy eye. Amblyopia happens when they eye does not work right with the brain. The brain will tend to favor one of the eyes over the other. Usually this will only affect one eye, but it has been found in some cases that it can affect both eyes. The eye will look normal.
Amblyopia is one of the most common visual impairments found in children. This tends to begin during infancy and early childhood. Around 2 to 3 children out of 100 will have amblyopia. Also, 2 to 3 percent of people in the United States have some sort of degree of amblyopia.
There are some different causes of amblyopia. It can result from any visual condition that prevents the eye from focusing clearly. First, strabismus which is when both of the eyes do not line up. With this the eyes can either cross in which is esotropia, or they can cross out which is exotropia.This seems to be the most common cause. Next, a refractive error in the eye which is when one eye cannot focus like the other can. This can include nearsightedness, farsightedness, and astigmatism. Lastly, cataracts which is the clouding of the lens of the eye. There is an ability for the eye to focus light on the retina.
Sometimes this can be hard to diagnose. Usually, it is found during a visual exam. It is important to find this and treat it early because the reduction of vision will most likely be avoided. If it is not treated it could lead to things such as legal blindness.
There are a few different treatment options for a person to choose from. The treatments will force the person to use the eye that has the weaker vision. First, a person could wear a patch. The patch will be worn for about two hours a day and will last for weeks to as long as months. Another option is to have drops of atropine put into the stronger eye and causes blurred vision. Glasses also seem to help or even surgery. Unfortunately, there are very few studies on treatments for adults.
3. Terms: Ambylopia, Retina, Strabismus, Nearsightedness, Farsightedness, Astigmatism, Cataract, Esotropia, Exotropia
Atropine
4. https://www.youtube.com/watch?v=P4pXMjqs12o
I chose this video because is was very clear and to the point about what ambylopia was, what the causes were, and what the different treatments were.
https://www.nei.nih.gov/health/amblyopia/amblyopia_guide
I chose this site because it added more information about adults and what age range benefited from wearing an eye patch.
http://www.allaboutvision.com/conditions/amblyopia.htm
I chose this site because it had the same information as the others but explained it in more detail than the others.
My topic: Development of Spatial Vision (Infant Vision)
The development of vision relates to the chapter because chapter three talks about the eye and the visual system in great detail. I am interested in it because my brother and sister-in-law just had a baby and my family always talk about how my niece (the baby) are in awe of bright colors and cool patterns. After reading this chapter, I would like to know more about the development of an infant’s visual system.
It is obvious that at birth, babies cannot see as well as older children and adults and this is because their visual system and eyes are not fully developed. One reason is due to the nerve cells in the retina connecting to the brain not being developed. Studies provide evidence that an infant’s acuity estimates between 20/400 to 20/800.There are different stages in which babies can see objects. At birth to four months, babies typically don’t see anything or focus on anything further than 10 inches from their face simply because their eyes do not have the capability to do so. During this time, the baby’s eyes begin to work together and vision starts to improve. Also during this time, hand-eye coordination begin to develop and you will see this when the baby starts trying to grab for objects in sight. It is said that by eight weeks, the baby can more clearly see the faces of their parents or another person near them when being held. It is common for the baby’s eyes to seem cross eyed or wander a little bit. This is usually normally but there are conditions to look for. If the baby’s eyes turn in or out constantly, it should probably be checked out.
Between the ages of five to eight months, control of eye movements and hand-eye coordination improves and continues to improve. Also around the fifth month, a baby’s depth perception begins to improve. It is easier for them to judge the distant of objects around them. This capability develops when the babies eyes work together to cultivate a three dimensional view of the world. Color vision is also not developed at birth. It takes about five months to develop the colored vision for a baby. As soon as babies start crawling, it is another way to develop vision and hand-eye-foot-body-coordination. A theory that I find very interesting is the theory that babies who did less crawling because they learned to walk earlier than other babies actually have poorer eye conditions.
After these stages, babies learn to walk and talk and are familiar with grasping things to help them stand. All of these things continue to develop over time. The development of our visual system is very important because it is the reason for how good or how bad we see.
http://www.aoa.org/patients-and-public/good-vision-throughout-life/childrens-vision/infant-vision-birth-to-24-months-of-age?sso=y – I liked this website because it was sectioned off into month by month stages of spatial development and gave me a better understanding of visual development of infants.
http://www.allaboutvision.com/parents/infants.htm - I liked this website because it also was broken down to certain month increments that helped me better understand the developmental stages of vision in babies.
http://psych.ucalgary.ca/PACE/VA-Lab/Marcela/Pages/page35a.html - I used this website because it had many terms I was familiar with and terms that related to the book. I could compare what I knew from the book with what I read from this website. It helped expand my knowledge of terms and their definitions that fit with spatial vision in infants.
I forgot to list the terms.
Terms: Spatial development, retina, cornea, visual system, hand-eye coordination, acuity, 20/400, 20/800, vision, color vision.
The topic I picked to research is the impact of mild traumatic brain injury (aka concussion or TBI) on the primary visual cortex/striate cortex. This topic relates to the chapter as the book made a big deal about how important this area of the brain was to vision (both topography and magnification). I am interested in this topic as when I was reading about the inion I realized that was where I hit my head when I got a concussion in high school and noticed how my vision got worse after the concussion.
First off, here are some concussion basics as many people have a rough idea of what a concussion and its symptoms, but there is more to it than the general public might know the brain is surrounded by cerebrospinal fluid. This fluid has one job: help protect the brain from being injured because the skull was hit/hit something. In the case of the brain actually colliding with the skull: the brain injury is consided to be a diffuse axonal injury (as opposed to focal brain injury) because damage and pain happens around the physically impacted area, not just the spot on the head that was hit. Concussions are actually very common, even outside the sports world, as 30% of people will have had at least one concussion by the age of 25. Apparently it is estimated that a person gets a concussion every 21 seconds in the US alone. Concussions are most likely to happen to: infants/young children (because of how unsteady they can be on their feet while learning new ways to move or during growth spurts) and people 15-29 years old. It is important to note that many of these stats may be incorrect or skewed due to how prevalent underreporting is; this could be due to fear of being removed from sports or just that people don’t go to the doctor to deal with their concussion.
I was surprised to find out that there are three levels (grades) of concussions u: I, II, III. Grade I is when the patient shows symptoms for less than 15 minutes and the person does not lose consciousness. When the symptoms last for more than 15 minutes without a loss of consciousness that concussion would be classified as grade II. Most people who experience these grades can possibly recover on their own but. People who experience grade III concussions will not fully recover without medical attention, as they lose consciousness. Illa if the person regain consciousness after a few seconds and Illb if the person regains consciousness minutes later. Despite the distinctiveness of this grading system, all people who suspect they received a concussion should go to the doctor as only a doctor can accurately figure out the severity of persons’ symptoms and the risk of long term injuries. This can be difficult as there in no universal classification system since the medical authorizes around the world have had difficulties deciding on one system, in fact there ae currently 41 in use around the world. The one I described above is the system used by medical professionals in the US: the American Academy of Neurology.
I also discovered that that there are different types of TBIs. The first type is called Inertia injury, this type is caused by a sudden acceleration or deceleration that causes the head to be hit. The second type is called impact injury; this type is caused by an object hitting the skull. The third type is called penetrating injury, this type is caused by a foreign object entering the skull.
The symptoms of concussions can impact every aspect of the patient’s life and can be quite severe depending on the grade and location where head was hit. The physical symptoms include: headache, vomiting, nausea, dizziness, balance problems, increased clumsiness, light sensitivity, blurred vision, double vision, and tinnitus (ringing in the ears). The cognitive symptoms include: confusion, difficulty concentrating, slurred speech, a general slowing down of reasoning skills and post-traumatic amnesia. The emotional symptoms are: increased moodiness/mood swings. restlessness, fatigue, and an increased chance of developing depression(short and long term). There are some symptoms that harder to classify as they impact all aspects of life: sleep disturbances (being excessively tired, or insomnia like symptoms), changes in appetite and general differences in usual behavior/personality. Most of the above symptoms will get better after around 3 months at the latest depending on the severity of the concussion. But it is possible that some symptoms could take years to go away or even become permanent, which is when post-concussive syndrome comes into the conversation. The usual symptoms of this are: headaches, dizziness, fatigue, memory/attention deficiencies, anxiety, sleep disturbances, and increased irritability.
I thought the function of the optical lobe after a grade III concussion was interesting. The optical lobe is the area of the brain where the primary visual cortex is, which is why a server blow to this part of the skull could be very dangerous, the symptoms of blurred and double vision for example. If there is too much damage, the person with the concussion could go blind despite the fact that their eyeball and the parts the eyeball contain are all in working order. This disorder is called cortical blindness (could be total or partial), since it only happens when the blood flow is cut off to the optical lobe.
Terms: mild traumatic brain injury , concussion, TBI, visual cortex, striate cortex, vision, topography, magnification, inion, cerebrospinal fluid, skull, diffuse axonal injury , focal brain , injury, underreporting, grades, I, II, III, Illa, Illb, severity, American Academy of Neurology, Inertia injury, acceleration, deceleration , impact injury, penetrating injury, physical symptoms , headache, vomiting, nausea, dizziness, balance problems, increased clumsiness, light sensitivity, blurred vision, double vision, tinnitus, cognitive symptoms , confusion, difficulty concentrating, slurred speech, a general slowing down of reasoning skills, post-traumatic amnesia, emotional symptoms, moodiness/mood swings, restlessness,, fatigue, depression, sleep disturbances , insomnia, behavior/personality, post-concussive syndrome, optical lobe , eyeball, cortical blindness , total, partial.
http://www.webmd.com/brain/concussion-traumatic-brain-injury-symptoms-causes-treatments?page=2 --I used this source for information on the grading systems and symptoms.
http://en.wikipedia.org/wiki/Concussion-- I used this source for a lot of the basic info about concussions, the grading systems, symptoms and post-concussion syndrome...
http://www.ncbi.nlm.nih.gov/pubmed/25387354 --I used this source for one statistic and I chose it because it comes from a respected source.
http://neuroscience.uth.tmc.edu/s4/chapter12.html --I used this source to identify the different types of TBIs, some stats, optical lobe damage,
http://en.wikipedia.org/wiki/Cortical_blindness- I used this source to identify problem that causes cortical blindness.
http://www.concussiontreatment.com/concussionfacts.html#sfaq9 – I used this source to provided group names for the symptoms.
http://braininjuryhelp.com/parietal-lobes-occipital-lobes/ -- I used this source to learn about possible problems that happen when the occipital lobe ( and the primary visual cortex by extension).
This week for my topical blog I choose to look farther into the tilt aftereffect. This relates back to the chapter as they took a section of the chapter to explain. The book starts of with explaining how our eyes adapt in certain situations and how they perceive the information. I find this interesting because our eyes are such an interesting and complex topic as it is but to figure out how our eyes adapt in situations has always been a particular part of interest to me.
The tilt aftereffect is a visual phenomena, if you were to stare at a figure with lines straight up and down after time the lines will appear to have a slight tilt in the opposite direction. People often look at this definition and think to themselves that this is just some simple concept but in all reality it is much deeper with information than that. The tilt aftereffect is more complex than just looking at a picture and after a period of time the image moves.
The visual system is able to accurately measure the orientation of lines and edges. The tilt aftereffect is a visual illusion which looks at the adaptation to an oriented visual stimulus that causes the stimuli to appear rotated away from the original position. It comes from the preferred orientations of neurons and they shift away from the adapting orientation.
The effect on the tilt can be detected by measuring how the electrophysiological of a single neuron to the test stimuli are being changed by the context. The electrophysiological will be able to indicate if the stimuli suppresses or enhances the neuron firing rates as the orientation tuning change as a result to the tilt aftereffect. The psychological evidence can also be looked into using a fMRI on the tilt aftereffect after long term adaptation to an oriented grating.
What most people look at is actually called the tilt illusion and when the illusion is successful the illusion then becomes known as the tilt aftereffect. The theory that comes for these effect attributes to lateral interactions between orientation specific feature detectors in the visual cortex. It is believed that the inhibitory connection strengths between activated neurons to temporarily while focusing on the input of the pattern. Overall this is saying that as we look at the pattern on the paper the neurons are focusing on the the idea of the pattern and over time the neurons becomes weak and tired and from this it causes the tilt aftereffect and the image then becomes tilted.
http://nn.cs.utexas.edu/web-pubs/bednar.thesis/node4.html- This website gave me alot of information about what the tilt aftereffect is and how it was developed.
http://jn.physiology.org/content/94/6/4038 this website was harder to understand and use into my information as it was more of a study but it still gave me good information about the actual patter and how it effected the visual system.
http://en.wikipedia.org/wiki/Visual_tilt_effects this website looked more into the psychological evidence that came about with the tilt aftereffect.
Terms: visual system, stimulus, neurons, electrophysiological, stimuli, fMRI, Visual Cortex, Inhibitory connection,
1a) State what your topic is.
My topic is amblyopia.
1b) Discuss how the topic relates to the chapter.
This topic relates to the chapter because it was mentioned in the sections on having a problem between the brain and eye working together which creates a problem with vision. The vision in one eye is reduced because the eye and the brain are not working properly together like they should. The eye itself looks normal, but it is not being used normally because the brain is favoring one eye. It can sometimes be called a lazy eye.
1c) Discuss why you are interested in it.
I am interested in this topic because I have a friend with a lazy eye condition. I’ve always generally wondered what’s caused it and if there are any treatments for it. My assumption has always been that there aren’t any treatments if people don’t get it corrected but at the same time it could just be a case that it’s extremely expensive and insurances don’t cover it.
With this condition, the person doesn’t send as many neuro-electrical signals to the brain with the lower functioning eye. This can be caused by a number of reasons. The under-usage of the neural pathways damages the ability for one of the eyes to see normally.
It can be caused by the misalignment of the two eyes, which is a condition called strabismus. With strabismus, the eyes can cross in, which is esotropia, or turn out, which is exotropia. Sometimes amblyopia is caused by clouding of the eye, which is generally known as cataract. It can also occur when one eye is more nearsighted, farsighted, or has more astigmatism. These all refer to the ability of the eye to focus light on the retina.
There are actually several types of amblyopia as well. There is strabismic amblyopia, which develops when the eyes are not straight. Deprivation amblyopia develops when cataracts deprive young children’s eyes of visual experience. Lastly, refractive amblyopia, which happens when there is a large or unequal amount of refractive error in a child’s eyes. There all result in reduced vision.
Wearing glasses has been shown to possibly help the problem, but not completely correct it to 20/20. With amblyopia, the brain is used to seeing a blurry image and can’t interpret the clear image that the glasses produce. With time the brain can relearn but it would take an extreme amount of time. It’s best to treat it as early as possible so the brain can start to try to relearn.
Terms: Amblyopia, neuro-electrical, neural pathways, strabismus, esotropia, exotropia, cataract, nearsighted, farsighted, astigmatism, retina, strabismic amblyopia, deprivation amblyopia, refractive amblyopia, refractive error.
URL: http://www.aapos.org/terms/conditions/21
URL: http://www.preventblindness.org/amblyopia-lazy-eye
URL: https://www.nei.nih.gov/health/amblyopia
I chose these websites because they all had great information and I could easily compare the information to the book. They also went over the causes and different treatments. I was able to explore and learn a lot more about amblyopia with these websites.
I decided to do research on both anisometropia and amblyopia for this week’s topical blog. I first chose anisometropia as my topic, but then I realized I had to do amblyopia as well because they are very closely related. The book talked about both anisometropia and amblyopia. I am interested in the topics this week because I think I have a certain degree of anisometropia and maybe that’s what causes my double vision.
ANISOMETROPIA AND AMBLYOPIA
Amblyopia, sometimes called the lazy eye, is often caused by anisometropia, even though the mechanism of amblyopic anisometropia. Anisometropia is when the right and left have unequal refractive error (one eye is mildly nearsighted, and the other is severely nearsighted; or one eye is near sighted, and the other eye is farsighted), and there is at least a 1.0 diopter difference presented between the two prescriptions. When the difference between two eyes involves nearsightedness and farsightedness, amblyopia will be present due to the inability of one eye to focus as well as the other, thus causing the brain to favor one eye, leaving the other eye unused.
When two eyes have a significant amount of different refractive error in the vertical meridian, a differential prismatic effect at the same right and left visual points will move away from the optical centres, and this cause double vision because the fusion of the right and left visual fields cannot be sustained.
Since Anisometropia is the leading cause of amblyopia, scientists feel obligated to conduct studies on anisometropic amblyopia. There is no clear threshold for the degree of anisometropia to be present before amblyopia manifests itself. Some children develops amblyopia with mild anisometropia, and some children can tolerate a significant amount of anisometropia without developing amblyopia. With that said, the relationship between anisometropia and amblyopia is unclear. It was first thought that the factor determining the development of amblyopia is the blur that is caused by anisometropia (as the brain favors one eye and ignores the other), but the fact that people of different degree of anisometropia can develop amblyopia (as in no relationship found between the magnitude of anisometropia and amblyopia in patients) indicates that some other factors might play a role.
Some longitudinal studies showed that persistent or increasing anisometropia may play a role in the development of amblyopia, but it is still unclear whether early treatment for anisometropia has any effect on the development of amblyopia. It is possible that the increase in anisometropia may somehow be related to amblyopia that had preceded the development of anisometropia; or, some abnormalities in the eyes cause amblyopia before it manifest anisometropia as a result. A study showed that amblyopia may precede anisometropia by proving that the magnitude of anisometropia increases in people with strabismus (or crossed eyes, where eyes are not perfectly aligned with each other due to a lack of coordination between the extraocular muscles or strong preference of one eye).
Anisometropic amblyopia can be tested with different measures. When tested with receptive fields, patients display better visual acuity with isolated or single letter visual acuity than linear acuity, so patients may have difficulties in things of similar size in their surroundings, and spatial summation studies show larger neuronal receptive fields in the amblyopic visual system. When tested with contrast sensitivity, anisometropic amblyopia patients with mid and high spatial frequencies show decreased contrast sensitivity across the field (patients with strabismic amblyopia on the other hand, only show decreased in the central visual field). When testing with grating acuity and Vernier acuity, anisometropic amblyopic patients display decreased acuity. Several treatments are available for anisometropic amblyopic patients: refractive correction, patching, atropine, neutral density filter, and neuro-pharmocology.
TERMS: grating acuity, Vernier acuity, anisometropia, amblyopia, strabimus, nearsightedness, farsightedness, extraocular muscles, refractive error
http://eyewiki.aao.org/Anisometropic_Amblyopia
This website provides a lot of basic information regarding anisometropic amblyopia. It was the first good website I ran into that explains what anisometropia is, and it made me realize that I needed to do amblyopia as well.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1447580/
This website describes the relationship between anisometropia and amblyopia. It provides information regarding the studies that have been done on both topics and the correlation they found between the two.
http://en.wikipedia.org/wiki/Strabismus
At one point I needed to understand the mechanism of strabismus and this website provided me just the information I need.
http://www.strabismus.org/various_strabismus_treatments.html
This website provides the definition and description for anisometropia. I did not use much from this website but it gave me a big picture of what abnormality I am looking at.
http://www.college-optometrists.org/filemanager/root/site_assets/oip/14-1/6178_oip_vol_14_issue_1-2013_1_p1-10_mccarthy_interactive_d5_5.pdf
This is a research paper on anisometopia, although it was very difficult to understand but the information was very detailed and useful. I learned a lot from this paper.
https://www.nei.nih.gov/health/amblyopia
This website was the first good website I found when I decided to do this topical blog on amblyopia as well. It provided me with the information I need to understand the relationship between amblyopia and anisometropia.
1abc) The topic I decided to research is a condition called Amblyopia. It is sometimes referred to as “lazy eye.” From this previous chapter we talked a lot about our visual field so it made me think back to this condition and how it could affect our seeing ability. The reason why I am interested in this is because my husband has bilateral Amblyopia which just means it is in both eyes and he has told me a bit about the condition already. Fortunately for him he has 20/20 vision from some eye training he received as a child to better control it.
Amblyopia has been defined as a unilateral or bilateral decrease of visual acuity caused by deprivation of pattern vision. Amblyopia is a disorder of development of the visual system that can present with varying levels of severity and usually affects one eye only. The most common predisposing condition for amblyopia is strabismus which causes disruption of binocular vision development. Other causes include refractive error or, more rarely, media pacification causing reduction in image quality such as cataracts.
Amblyopia is more than four times as common in infants who are premature, small for gestational dates or who have a first degree relative with amblyopia. In infants with neuro-developmental delay, the prevalence of amblyopia is six times higher than in healthy, full-term infants. Similarly to my husband’s case he was a premature baby and the doctors believe that is what caused his.
The studies of early treatment intervention regimes allow better understanding of the natural history of amblyopia. The findings of people that undergo early intervention and treatment have lower prevalence of amblyopia than those that do not. This implies that amblyopia does not improve on its own. Some early on treatments include having the child wear an eye patch on the un afflicted eye, so it forces them to use their bad eye and strengthen it over time. We have already read from our chapter that when one eye is damaged the other eye overcompensates for it, making it more difficult to notice when something is wrong. Another option is surgery. The treatment options vary depending on the underlining cause. There are instances where a person that is diagnosed with amblyopia can gain 20/20 vision with eye training exercises, but is still visually noticeable that they have the impairment. For these cases they can opt for a surgery that would just position the eye back to the area it normally would be. If it is not urgent then many time insurance won’t cover this kind of surgery.
Terms: visual field, amblyopia, 20/20 vision, visual acuity, pattern vision, strabismus, cataracts
http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2005.tb05102.x/pdf This was a review article that gave a great general overview of the history, causes, and treatments used for amblyopia
https://www.youtube.com/watch?v=P4pXMjqs12o this video is just a condensed lesson of amblyopia and puts it neatly together.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC404107/ This was a study done on the effects of improving vision in adult amblyopia by perceptual learning
For this week’s topical blog post, I chose to learn more about peripheral vision. While reading the chapter, I got kind of lost on the information about peripheral vision and how it works, so I decided to find some other sources to help me understand it better. In chapter 3, we learn how our eyes interpret the visual world in terms of “stripes” created by varying frequency sinusoidal waves. The phase of a particular wave and where it lands on a given ganglion cell determines the cells response, but together we perceive an image of stripes. The chapter explains the biggest challenge to the periphery being visual crowding, or the jumbling of visual information in the periphery. Unable to distinguish objects that are ordinarily recognized easily, we are almost completely unable to ascertain any information from the periphery without redirecting our attention. The spatial ranking strategy dictates the priority and sequence with which our focus moves from central field to the periphery. Although less capacity is devoted to peripheral vision, overall performance is improved.
Peripheral vision is often studied by blocking a portion of the image or video from the central or peripheral field. Direction of gaze and eye movement are then measured to indicate where the individual’s attention is focused on. Because either the central or the surrounding imagery has been covered, it can be determined whether a subject in that area of the visual field was noticed or focused on. Collectively, these studies are referred to as gaze-contingent. In gaze-contingent studies, the visual information is normally blurred rather than left opaque. Strangely, this is based on the assumption that a blurred object in the peripheral field requires less response than does an attention-redirecting one. This assumption has not been empirically substantiated, however. It is interesting that such studies should be based on assumptions that do not have a scientific foundation.
Despite this, researchers have found that blurrier images, or visual information that is otherwise more difficult to understand, does not impact one’s ability to perceive objects in the periphery. In order to shed more light on the function of the periphery in perception, studies have been conducted on individuals with central vision loss. This effectively controls the central vs. peripheral vision in both groups – the group with normal vision reveal how perception relies on both to construct the images we see, the group with central vision loss reflecting the imagery perceived based only on visual information from the periphery.
In one particular case studying broad scene categorization, a group of individuals with age-related macular degeneration were used, so it can be assumed these individuals had normal eyesight for the majority of their lifespan. This reveals something about the function the brain plays in perception. These individuals can no longer see in the center of the visual field, however they, as have the control group of individuals with normal vision, have built up a large bank of information available for recognizing and making inferences. Unfortunately, the results of the study suggest individuals with AMD will have more trouble with scene recognition due to the loss of central vision, and they will not develop better periphery vision as a result of their condition. As we learned in the book, cones are cells mostly responsible for color perception and highly concentrated in the center of the fovea. On the other hand, the primary purpose of rod cells is for less intense light and in higher concentrated in the edge of the retina. As such, individuals with AMD are less able to utilize colors in scene categorization.
Terms: Periphery, frequency, sinusoidal wave, gaze, ganglion cell, visual crowding, spatial ranking strategy, capacity, eye movement, attention, gaze-contingent studies,
http://psycnet.apa.org/journals/xhp/41/1/167.pdf
Explores the role of blur in processing visual information and the effect it has on overall performance.
http://www.sciencedirect.com/science/article/pii/S0042698914000510
This study compares groups with normal vision to AMD to understand more about peripheral vision and its role in scene categorization.
http://ejournals.ebsco.com/Direct.asp?AccessToken=6VXV9LC893XLZNVKCF33KNJKF2OZ8CH9F9&Show=Object
Explains spatial ranking strategy and the tradeoff between peripheral vision accuracy and overall performance.
I chose the topic from the heading called “Some Perceptual Consequences of Cortical Magnification”, mainly focusing on visual crowding. This chapter was about how we see things around us and what limits our vision and how our mind perceives differences. In the case of cortical magnification our vision is scaled down in different areas. The area around the fovea is magnified compared to the peripheral area off to the sides. This means that while we can see some out of our peripheral we do not seen nearly as much or as accurately as we do in the area around the fovea. One effect of this is visual crowding, this is a negative effect of clutter on our ability to recognize objects from our peripheral.
The hot topic in many cities is distracted driving, especially pertaining to texting and driving. Many areas are making laws against it, there a numerous reports of very serious accidents where one driver was texting and driving. I wanted to look more into the science behind perhaps one reason that one could say with authority proves or comes very close to doing so, that it is impossible to observe the road effectively while texting.
To begin with we simply do not see the same quality out of our peripheral as we do in the center. If like in the book we are focused on the bulls eye, we will not see the objects off to the side as clearly. We still see things and sudden movements will make us shift to see what that object is, which makes for a nice feature to have at our disposal. However it does not see enough to do many of the things we are able to do with our main area of vision. One example given is that we cannot count with our peripheral. I tried it, and while I of course knew that I was holding up four fingers, I really could not count them and had to shift my vision to see them all, I did not really see them all out of my peripheral.
This becomes especially problematic when there are many objects in our peripheral. In one study researchers found that it was easy enough to distinguish an object or letter peripherally but became more and more difficult to distinguish as more flankers (other objects) were added. When a driver is on the road there are generally many things that would be in the peripheral. Some situations more than others but there are always a few things that appear off to the side of main vision. The places that we tend to see the most objects would be in slower speed areas in town, which really combats the argument that at slower speeds texting and driving is less dangerous.
The biggest problem with texting while driving is that the driver’s main focus becomes the phone. This means that at that point the entire road is in reality his/her periphereal line of sight. No longer is any of the road the driver’s main focus. I can think of no driving situation where this would not create a problem. I was really disappointed that there wasn’t more available on the web comparing this scientific evidence to support a ban on texting while driving. It seems that this argument would be enough to change laws nationwide.
Terms: cortical magnification, visual crowding, periphrial, vision, perceive, focus, fovea
This sight seemed to be an expansion of a text book on the subject.
http://whitneylab.berkeley.edu/PDFs/Whitney_Levi_2011_TICS.pdf
These two were studies conducted about visual crowding
http://www.sciencedirect.com/science/article/pii/S0960982211000340
http://www.sciencedirect.com/science/article/pii/S0042698907005561
My topic has to do with the development of spatial vision in infants and through childhood. This topic relates to the chapter because the chapter discusses spatial vision in infants to be a blooming, yet confusing topic that is hard to understand and measure. This topic interests me because my best friend just had a baby and I wanted to see her development of spatial vision over time.
My first source acknowledged that under certain testing conditions, the maturity for spatial and temporal vision occurs at different rates during childhood. Limiting information it relays to higher visual centers, the immature retina doesn’t limit the amount of spatial vision acquired. Post retinal immaturities have been present in non-human primates as testing subjects and these immaturities disrupt the pathway that account for the limitations measured in temporal vision. Also measuring acuity and frequency, frequency was found to mature earlier than sensitivity at lower spatial and temporal frequencies. So frequency reaches maturity much earlier than acuity. During childhood, temporal contrast sensitivity develops at a much faster rate than spatial contrast sensitivity.
My second source was a study to compare objective acuity and contrast sensitivity with visual evoked potentials. This source has a twist though compared to the first source. This study involved a group of children with Down Syndrome and a control group. The end goal was to determine if children with Down Syndrome have a sensory deficit when using a procedure that was less cognitively demanding than conventional tests. The results showed acuity thresholds were lower in the Down Syndrome group than the control group, they also had reduced contrast sensitivity and behavioral contrast sensitivity. This study with VEP’s and behavioral measures showed than Down Syndrome children do contain a sensory deficit, but the control group does not.
My last source tested acuity, contrast and sensitivity also. But the results were different. The study went on to say that there is an unexplained yet unimaginable gap between infant and adult sensitivity. The sensitivity loss or gain cannot be explained by age related changes in optics and receptors. Infant performance affected by the level of illumination from the study is not measurable. Different assumptions on the effects of illumination on acuity and contrast sensitivity lead to a lot of unpromising predictions.
http://www.sciencedirect.com/science/article/pii/S0042698998002806
This source provided me with information that showed how the development of spatial and temporal vision evolved throughtout childhood.
http://www.ncbi.nlm.nih.gov/pubmed/15111616
This source provided me with information on how children with Down Syndrome have a deficit in the acuity of vision along with sensitivity compared to the control group.
http://bankslab.berkeley.edu/publications/Files/front-end_spatial_vision93.pdf
This source showed that there is assumed that there is a lack of spatial vision in infants, but provided me with two analysis that showed there is a large limitation that delivers inadequate and unproven results.
Terms: contrast, acuity, spatial frequency, contrast sensitivity function
1a) State what your topic is.
Bottom up- Top Down Processing.
1b) Discuss how the topic relates to the chapter.
Bottom up and top down processing is another theory of how our mind goes through pattern recognition. I noticed a lot patterns within the chapter and how they are seen and processed.
1c) Discuss why you are interested in it.
I was googling a few things about pattern recognition, and I just happened to stumble onto up down processing. Originally I wanted to know more about how we process symbols, letters, patterns and so on.
2) Take the information you read or viewed related to your topic, integrate/synthesize it.
In the brain, top-down and bottom-up are not, actually, separate processes. Theorists artificially separate them in order to talk about them.
In terms of cognition, a bottom-up process occurs when something unexpected is moving in the corner of your eye and catches your attention. This causes you to look over and react. The signal causing this chain of events originated in the environment, at the bottom of the sensory processing stream.
A top-down process is like trying to find Waldo in where’s Waldo. You start with a high-level goal, which determines where you look next. You are looking for something, so higher-level brain areas prime the low level visual areas to detect that pattern.
In terms of how it works in the brain, the easiest way to think about is like a larger corporation. Bottom-up is the process by which the executive committee finds out what is going on in the marketplace. Front-line marketing and sales people notice patterns and trends. They talk about these trends with each other and with their managers. The managers talk with each other and with directors, who then talk with VPs, who in turn sit on the executive committee. So information bubbles up through the organization. Top-down is when the executive committee reaches a consensus that the company's product or business strategy needs to go in a new direction. The VPs on the committee implement changes with the directors, who reallocate the work of managers, who change the priorities of the front-line people.
Communication is happening in both up and down directions at all levels all the time. And there is communication that skips levels, and lateral communication within levels, and communication going to and from other brain areas.
One universal pattern in the cerebral cortex is that whenever one brain area has a pathway to another, there is always a reverse pathway back again. These bidirectional pathways allow two-way information flow to occur. So the reality is more like continuous directional and multi-way information flows, bottom-up signals originate with a change in the environment, and top-down signals originate with a new internal goal.
Resources:
http://en.wikipedia.org/wiki/Top-down_and_bottom-up_design
This was the main link I used for my information. It discusses the different approaches bottom up and top down processing takes. It also relates to neuroscience as well as gives examples of real world management and organization examples.
https://www.youtube.com/watch?v=4-4CAqXlVXo
This video gives a really simple explanation of both processes. It also gives many interesting examples, and enters the idea of priming and processing.
http://www.intropsych.com/ch07_cognition/top-down_and_bottom-up_processing.html
This link goes along with the video somewhat. It gives introduction to both processes, but explains where the “rat-man” came from and how priming can lead to different results when thinking in terms of top-down processing.
My topic is amblyopia. It pertains to the chapter, because it is a visual impairment and is actually briefly discussed in the reading. I am interested in it, because I know several people who are affected by it.
Amblyopia, more commonly known as "lazy eye", is when one eye suffers lesser vision, because it does not work properly with the brain. They eye may even look entirely normal, but the brain will favor the other eye. This can happen if one eye sends a blurry image to the brain. The brain then becomes accustomed to only seeing blurry images with that eye, so it relies on the other eye for visual input. There are three types of amblyopia: strabismic, deprivation, and refractive. Strabismic amblyopia is due to one eye not seeing straight with the other eye. This is the type that is easily recognizable, because the eyes will point in different directions. This is the one that is most commonly associated with the term "lazy eye". With this condition, the brain will essentially shut down the eye that does not point straight so the vision in that eye drops significantly. The second type, deprivation amblyopia, is due to cataracts or other similar conditions that lower vision in the eye. The third type, refractive amblyopia, is when there is a large or unequal amount of refractive error in the eye. The brain will again, in a way, disable the bad eye. While amblyopia only occurs in children, if not treated quickly, it may cause permanent damage to the person's vision. If the condition persists or is not treated early enough, the brain will become accustomed to seeing better with one eye and always favor it. Because of the nature of neural development, if one eye does not see as well as it should, the "wiring" for that eye will not develop properly. Once a certain point is reached, that wiring can never be developed, so the eye will never see as well as it should. Deprivation amblyopia is treated by surgically removing the cataract so that the eye can see and develop normally. The most common treatment strategy for the other types is to force use of the bad eye, so that the brain does not favor the other eye over it. This can be done by putting a patch over the good eye or placing a drop of atropine in the stronger eye to temporarily blur its vision. Wearing glasses may help in some cases but will never restore vision to the "perfect" 20/20 benchmark.
Terms: Amblyopia, Strabismic, Deprivation, Refractive, Cataracts, Atropine, 20/20
https://www.nei.nih.gov/health/amblyopia/amblyopia_guide I used this source, because it provides a good base for the general information without bombarding one with the deeper details.
http://www.aapos.org/terms/conditions/21 I used this source, because it provided a fairly in-depth view into the condition and was organized in an easy to read fashion.
http://en.wikipedia.org/wiki/Amblyopia I used this source, because it went into much more detail on some aspects of the disorder than the other sources.
1a. The topic from chapter three that I have chosen to focus on is the critical period of vision. Researchers Hubel and Wiesel found that monocular form deprivation resulted in massive changes in cortical physiology that caused permanent loss in spatial vision. This research and others like it found evidence to suggest that their is a critical period for early visual development when normal binocular visual stimulation is required for normal cortical development. For humans this critical period takes place between three and eight years of age. During this time of plasticity, the visual development of cortical neurons is still being wired to the specific locations of the neurons in each eye. If one eye is not receiving normal stimulation for a prolonged period of time it is possible for abnormal visual experiences to occur. This extended period of time experiencing abnormal vision results in neurons being unable to properly connect to their destined location and causes them to instead form abnormal wiring connections that cannot be repaired.
1b. This topic relates to chapter three because it discusses vision and the effects that deficits have on long term visual acuity. It explains visual deficits and how they effect the visual system as a whole.
1c. I am interested in this topic because I think critical periods are very important components of human development to understand. There are many benefits for society when critical periods are discovered and researched. It allows doctors and parents to make sure they are adequately providing care to children during these important times. It also aids in the the ability for doctors to monitor children during these critical periods to ensure healthy and normal development. Additionally, I think it is very interesting to look at this topic from a neurological perspective. Abnormal vision experienced for a long period of time changes the connections of cortical neurons permanently. All of these aspects of vision critical periods make it an interesting and relevant topic.
2. In an article by Levi et al., the researchers aimed to look at the effects and treatment options of a neuro-developmental disorder known as Amblyopia. It is a disorder of the visual cortex that arises from prolonged abnormal visual experiences during the critical period of vision development. This disorder is especially important because it is the most common visual impairment found in infants and children. It is also reflects the impairment that occurs when normal visual development is disrupted. It is an ideal model for understanding the critical period as well as brain plasticity during childhood. It is additionally the subject of new forms of treatment that can reverse the damage of the cortical neurons after the critical period has ended. Up until this point there have been no therapies available to effectively diminish the damage when the critical period has ended. The current study chose to look at stereopsis specifically to determine the treatment options with the best results. Individuals with amblyopia characteristically experience impaired stereoscopic depth perception and as a result suffer from impacted visuomotor skills, difficulty playing sports if the patients are children, and difficulty navigating in every day life as well as troubles sustaining a job if the patients are adults. The current research found that therapies such as perceptual learning, patching, and video gaming are promising new approaches to recovering from amblyopia in patients that are currently in the critical period of vision development as well as patients who have passed it. More research needs to be done to determine the efficiency of these treatments as well as other valid options. Another article by Hou et al., found that visual development depends on sensory input during an early developmental critical period. To learn more about the effects of visual depravation on the development of the visual cortex the researchers utilized event-related potentials (ERP's). Results of the study indicated that deprivation during cortical development effects every aspect of long term visual development. This finding is important because it exemplifies the importance of finding these abnormalities when they can still be reversed and treated properly. An article by Kiorpes solidified the finding that the visual system has critical periods associate with its development. She specifically found that different structures in the visual system have different critical periods which gives way to new research and the development of effective treatments.
Terms from book and articles: monocular form deprivation, cortical physiology, critical period of vision, plasticity, cortical neurons, amblyopia, stereopsis, visuomotor skills, ERP's,
http://www.ncbi.nlm.nih.gov/pubmed/25637854
http://web.a.ebscohost.com.proxy.lib.uni.edu/ehost/detail/detail?vid=4&sid=c30f69bb-995c-47b1-b07c-363a6d883460%40sessionmgr4003&hid=4212&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=psyh&AN=2014-31731-007
http://www.journalofvision.org/content/4/11/31.abstract
The topic I choose to research for this blog is Amblyopia or "lazy eye" this was discussed in the book. Amblyopia is a condition that causes weakened vision in one eye for various reasons giving it the "lazy eye" effect. It is considered a failure for one eye to work properly with the brain, and therefore it is slowly weakened.
Amblyopia is the medical term used when the vision in one of the eyes is reduced because the eye and the brain are not working together properly. The eye itself looks normal, but it is not being used normally because the brain is favoring the other eye.A common cause of amblyopia is the inability of one eye to focus as well as the other one. Amblyopia can occur when one eye is more nearsighted, more farsighted, or has more astigmatism. Having this condition seems to be completely by chance and those that do have it can't seem to help it or change it in any way.
This condition can make things much more difficult for children growing up that have it than children growing up who don't. It can make tasks like reading the black board or catching a ball in baseball very difficult. I find this interesting because my cousins little boy Cyson is 2 and they are starting to notice that he might have a lazy eye but they had never noticed it before. They notice that when he looks at you he isn't looking with one eye as much as the other; the left eye tends to droop down more.
When diagnosed with amblyopia there are steps to take. Children who are diagnosed can't always be cured but sometimes they can undergo treatment to help make their weak eye stronger. Simple fixes such as glasses or contact lenses don't seem to be the answer for this. However, one treatment that seems to be working which I read about was an eye patch. Children with amblyopia would patch the eye that they have the issue with for a significant amount of time in order to hopefully make the eye stronger when the eye patch is removed. Early detection is key to success with these issues and it is helpful for the children's treatment with this issue.
Overall amblyopia is a serious yet livable condition that affects people all over the world. Parents need to make sure to take advantage of school eye check ups which should be provided through their public school but also they should have their babies eye's checked as young as 6 months old; then continually checked after that.
Terms:
Ambylopia, Retina, Strabismus, Nearsightedness, Farsightedness, Astigmatism, Cataract, Esotropia, Lazy eye,
http://www.aafp.org/afp/2007/0201/p361.html
http://kidshealth.org/parent/general/eyes/amblyopia.html
https://www.nei.nih.gov/health/amblyopia
Visual Crowding
There is a limit to how many objects we can clearly perceive. Our vision generally seems clear most of the time but this is an illusion. Our eyes quickly glance over areas in our visual field and our brains hold on to that image to create our peripheral vision. Don’t get me wrong, we can see out of the corner of our eyes but the image our periphery can produce isn’t in color and is only general shapes and distances. Our brains subconsciously fill in the gaps with memories and guesses to complete a fully colored, high resolution image. We can reveal this illusion by the concept of visual crowding. This is when we cannot identify or count objects in our periphery due to the number or proximity to other objects. This is due to the extreme decrease in visual acuity in our peripheral vision. The center of the fovea, the center of the retina, has the highest concentration of cone cells. These cells account for our “high-resolution” vision or high acuity. These sensory cells require high levels of light and can sense colors of light as well as detail. Our periphery is mostly rod cells, these neurosensory cells require less light and sense general detail in our environment. Our brains synthesize the input from all these cells and create the image of the environment around us that we perceive. Since rod cones cannot see great detail, visual crowding is a factor in our overall vision. If multiple objects are in our peripheral vision and are close in proximity to each other, our eyes cannot sense the details between the objects. Since the light from the objects only hit our rod cells on our retina the objects clump together and are indecipherable. In order to compensate for this downfall in vision we have to quickly glance at the clump and in mere milliseconds can perceive the objects for what they truly are.
Terms: peripheral vision, acuity, fovea, retina, cone cells, rod cells
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3070834/
http://www.sciencedirect.com/science/article/pii/S0042698907005561
http://www.journalofvision.org/content/7/2/14.full
1a) State what your topic is.
My topic is on The Lateral Geniculate Nucleus.
1b) Discuss how the topic relates to the chapter.
This topic is relate to the chapter because it talks about the axons of the retinal ganglion cells, it also talks about the left and the right hemisphere of the visual system, the LGNs have six layers on both sides that construct differently but yet all are working the same goal, which is for someone to see exactly like how they're supposed to see.
1c) Discuss why you are interested in it.
i'm interested in this topic because i want to understand how this part of the visual system is connected to the visual fields and how the thalamus actually has a lot to do with this connection. LGNs are very complicated to understand and they are actually a structure of the thalamus making them part of the midbrain, they receive input from the retinal ganglion cells and they also have output connections with the visual cortex, i think those things are pretty interesting things to learn how each of them work.
2) Write about your findings
As i was looking at some some of the findings about LGNs, it results that these two hempshere work very well together but they have a different way of generating. there are two types of the separation, the right and the lift field, or the parvocelluar layers and the magnocellular layers. the eurons in the bottom two layers are phsyically larger than those in the to four layers (look at the second website to see ) the bottom two of the layers are called the magnocelluar layers and the top four are called the parvocellar layers. the M layers receive input from the Ganglion cells in the retina, and the P layers receive their from the P area of ganglion cells. these also go through the cerebral cortex. (look at website 3) this usually confuses people on how the cerebral cortex is connected to the LGNs, but the thing is that LGNs actually help the Cerebral Cortex more than they help the visual fields, those six layers on both sides are the ones helps function your sleeping pattern correctly at night and that would be the work they do through the cortex. when the LGNs send signals to the cortex, it completely shuts off everything in your sleeping paths, it helps you go to sleep and stay asleep, unless the LGNs are contacted by the ganglion cells to be activate or do something, or even be aware of your surroundings. an example of this would be waking up to a noisy situation when you're sleeping, your LGNs would be send a signal from the thalamus, telling them its time to shut down and sleep, the cortex will send signals to the ganglion cells, and the ganglion cells will go through a process helping the eye to shut down so it can match your brain and your body, but as soon as the ganglion sense there might be danger or noise that's very loud, they send a signal to the thalamus and the thalamus go to your LGNs and make them aware.
i think overall this is a very important part of this chapter, not only for the visual part of it, but also for the fact that it has some connection with your brain, the cerebral cortex.
TERMS: LGNs, Magnocellular layers, Parvocellular layers, Contralateral, Visual fields, visual system, cortex, cerebral, thalamus, hypothalamus ganglion cells.
http://www.lifesci.sussex.ac.uk/home/George_Mather/Linked%20Pages/Physiol/LGN.html
This is one of the websites that I came across on, basically it breaks down how the LGNs works and the many layers that LGNs have.
http://www.cns.nyu.edu/~david/courses/perception/lecturenotes/V1/lgn-V1.html
This sites take you through the whole process of the visual field on LGNs, also how it’s connected to your cerebral cortex, and thalamus.
http://compneuro.umb.no/wiki/Research/LGN%20receptive%20fields
Last but not least is this study that was done on the LGNs circuit basically showing how everything comes together and where LGNs affect the most.
Topic: Development of Spatial Vision (Infant Vision)
The development of vision relates to this chapter because we start to discuss which structures of the eye do what, and what the processes are for each of them. I am interested in this because I have twin boys. They are almost three years old, and yet they are twins, they are fraternal twins. From the time they were small infants up to now, they both have had different reactions to looking at various stimuli. After reading this chapter, I would like to know more about the development of an infant’s visual system and up through early adulthood.
This chapter does not go into great detail about the development of spatial vision. As our book states "until recently, many people, even some experts, thought that infants could not see very much. This idea is not new. William James, the great 19th century philosopher and psychologist, argued that the visual world of infants is a "booming, buzzing confusion." As a parent I remember telling my wife (birth to 6 weeks roughly) that the boys can't really see us. This is a common belief among many people and even experts. It's not that they cannot see us, it's that babies can't distinguish depth-perception and contrasts very well. In fact, new born babies can see objects 8-12 inches away, anything beyond that is blurry. Infants first develop fine depth perception at 3 to 5 months of age. New born babies do not have the muscle control to move their ciliary muscles. So often times in the first days to even the first few weeks, babies will often time cross their eyes or blink out of sequence. Every movement they start out with, they can only improve on. That is the amazing significance of our brains! At birth, babies can see colors but cannot distinguish the contrast on tones such as red and orange. The fovea is very immature at this time and cannot filter the process to the brain. By four months of age, babies start to work on their depth perception and he has both the motor development to handle the task and the maturity in his brain circuitry to coordinate all the moves needed to accomplish it. Their visual acuity is dependent on the optical components of the eye (like the lens), but more importantly it is dependent on the functioning of the retina and the brain. This means that even thought the optics of the eye are mature, infants still can’t see as well as adults because brain areas responsible for vision are still immature.
By eight months, an infants vision is almost adult in its clarity and depth perception at this point. Though his attention is more focused on objects that are close by, his vision is strong enough to recognize people and objects across the room. Compare this to at birth, their eyesight is between 20/200 and 20/400. By 4 months of age, acuity has improved by a factor of 2, that is to 20/60 vision. By 8 months of age, the nervous system has matured enough to improve acuity by a factor of 2 again, that is to 20/30, and is now nearly as good as normal adult acuity (20/20). Over the next several years, acuity improves gradually to adult levels; but the most dramatic change is over that first 8 months! Very young babies visual acuity is 6 times worse than adult acuity. Again, this is not because infants cannot "focus" (retina) well. Rather, it is limited by immaturities in the nervous system.
This weeks research topic got me thinking about my twins visual system more. My boys were born about 6 weeks early. Knowing there is so much research out there, I found a study that was interesting for measuring pre-term infants:
"In this study, they are investigating the development of vision and refractive error in infants who were born prematurely. Nearsightedness is a frequent problem among children who have been born early. We believe that the retina, which is affected by retinopathy of prematurity, governs whether the eye will grow to become nearsighted (myopic) or farsighted (hyperopic). Therefore, we are conducting a study of retinal function of premature infants, some of whom had retinopathy of prematurity and others who had no retinopathy. We would like to follow each child with tests of retinal function and measurements for myopia or hyperopia starting at age 10 weeks post-term and continuing until age 3 years. We would like you to consider having your child participate in the project outlined below. Baseline Examination at 10-weeks post term . For this examination, your child's vision will be checked with the preferential looking test (PL). Then dilating drops, like those used for their eye examination in the nursery, will be used. These drops are needed to obtain accurate measurements of the focus of the eye to determine if there is any myopia or hyperopia. It takes the drops about 30 minutes to work. At the end of the 30 minutes, we will check your child's dark adapted threshold (DAT) by showing spots of dim light and determining the dimmest light that your child will look at reliably. This test measures retinal function in small patch of retina. After this, we will check the function of the whole retina using either the full-field electroretinogram (ERG) or the multifocal ERG (mfERG). Anesthetic drops will be placed in one eye and a contact lens electrode placed on the surface of that eye. We will then record the electrical response of the retina to a series of blue and red flashing lights or flickering patterns."
I didn't know what other way to put this study in this assignment without copy and pasting the entire study in here. The study is outlined with quotes. It's amazing how much our technology and curiosity is ever growing and changing. To know that there could be a dramatic difference in the visual systems of term and pre-term infants through their life is amazing. I may have jumped a little all over the place in this blog, but it was hard to focus on one concept without knowing the background of something else.
References:
http://www.babycenter.com/0_baby-sensory-development-sight_6508.bc I chose this website because it gave a breakdown on the stages of site. Although it is not very scientific, it did expose which months infants had their development.
http://www.ski.org/Vision/babyvision.html I chose this site because it corresponded well with the previous site. I could see more of the structures being affected in this article.
http://www.infantvision.org/vision.htm#children I chose this article because of the Case Study for pre-term infants.
Terms: Spatial Vision, visual acuity, stimuli, depth-perception, ciliary muscles, contrast, tones, retina, lens, fovea, nearsighted, farsighted, myopic, hyperopic, Preferential Looking Test (PL), Dark Adapted Threshold (DAT), electroretinogram (ERG), multifocal ERG (mfERG)
My topic: Development of Spatial Vision (Infant Vision)
The development of vision relates to this chapter because we start to discuss which structures of the eye do what, and what the processes are for each of them. I am interested in this because I have twin boys. They are almost three years old, and yet they are twins, they are fraternal twins. From the time they were small infants up to now, they both have had different reactions to looking at various stimuli. After reading this chapter, I would like to know more about the development of an infant’s visual system and up through early adulthood.
This chapter does not go into great detail about the development of spatial vision. As our book states "until recently, many people, even some experts, thought that infants could not see very much. This idea is not new. William James, the great 19th century philosopher and psychologist, argued that the visual world of infants is a "booming, buzzing confusion." As a parent I remember telling my wife (birth to 6 weeks roughly) that the boys can't really see us. This is a common belief among many people and even experts. It's not that they cannot see us, it's that babies can't distinguish depth-perception and contrasts very well. In fact, new born babies can see objects 8-12 inches away, anything beyond that is blurry. Infants first develop fine depth perception at 3 to 5 months of age. New born babies do not have the muscle control to move their ciliary muscles. So often times in the first days to even the first few weeks, babies will often time cross their eyes or blink out of sequence. Every movement they start out with, they can only improve on. That is the amazing significance of our brains! At birth, babies can see colors but cannot distinguish the contrast on tones such as red and orange. The fovea is very immature at this time and cannot filter the process to the brain. By four months of age, babies start to work on their depth perception and he has both the motor development to handle the task and the maturity in his brain circuitry to coordinate all the moves needed to accomplish it. Their visual acuity is dependent on the optical components of the eye (like the lens), but more importantly it is dependent on the functioning of the retina and the brain. This means that even thought the optics of the eye are mature, infants still can’t see as well as adults because brain areas responsible for vision are still immature.
By eight months, an infants vision is almost adult in its clarity and depth perception at this point. Though his attention is more focused on objects that are close by, his vision is strong enough to recognize people and objects across the room. Compare this to at birth, their eyesight is between 20/200 and 20/400. By 4 months of age, acuity has improved by a factor of 2, that is to 20/60 vision. By 8 months of age, the nervous system has matured enough to improve acuity by a factor of 2 again, that is to 20/30, and is now nearly as good as normal adult acuity (20/20). Over the next several years, acuity improves gradually to adult levels; but the most dramatic change is over that first 8 months! Very young babies visual acuity is 6 times worse than adult acuity. Again, this is not because infants cannot "focus" (retina) well. Rather, it is limited by immaturities in the nervous system.
This weeks research topic got me thinking about my twins visual system more. My boys were born about 6 weeks early. Knowing there is so much research out there, I found a study that was interesting for measuring pre-term infants:
"In this study, they are investigating the development of vision and refractive error in infants who were born prematurely. Nearsightedness is a frequent problem among children who have been born early. We believe that the retina, which is affected by retinopathy of prematurity, governs whether the eye will grow to become nearsighted (myopic) or farsighted (hyperopic). Therefore, we are conducting a study of retinal function of premature infants, some of whom had retinopathy of prematurity and others who had no retinopathy. We would like to follow each child with tests of retinal function and measurements for myopia or hyperopia starting at age 10 weeks post-term and continuing until age 3 years. We would like you to consider having your child participate in the project outlined below. Baseline Examination at 10-weeks post term . For this examination, your child's vision will be checked with the preferential looking test (PL). Then dilating drops, like those used for their eye examination in the nursery, will be used. These drops are needed to obtain accurate measurements of the focus of the eye to determine if there is any myopia or hyperopia. It takes the drops about 30 minutes to work. At the end of the 30 minutes, we will check your child's dark adapted threshold (DAT) by showing spots of dim light and determining the dimmest light that your child will look at reliably. This test measures retinal function in small patch of retina. After this, we will check the function of the whole retina using either the full-field electroretinogram (ERG) or the multifocal ERG (mfERG). Anesthetic drops will be placed in one eye and a contact lens electrode placed on the surface of that eye. We will then record the electrical response of the retina to a series of blue and red flashing lights or flickering patterns."
I didn't know what other way to put this study in this assignment without copy and pasting the entire study in here. The study is outlined with quotes. It's amazing how much our technology and curiosity is ever growing and changing. To know that there could be a dramatic difference in the visual systems of term and pre-term infants through their life is amazing. I may have jumped a little all over the place in this blog, but it was hard to focus on one concept without knowing the background of something else.
References:
http://www.babycenter.com/0_baby-sensory-development-sight_6508.bc I chose this website because it gave a breakdown on the stages of site. Although it is not very scientific, it did expose which months infants had their development.
http://www.ski.org/Vision/babyvision.html I chose this site because it corresponded well with the previous site. I could see more of the structures being affected in this article.
http://www.infantvision.org/vision.htm#children I chose this article because of the Case Study for pre-term infants.
Terms: Spatial Vision, visual acuity, stimuli, depth-perception, ciliary muscles, contrast, tones, retina, lens, fovea, nearsighted, farsighted, myopic, hyperopic, retinopathy, Preferential Looking Test (PL), Dark Adapted Threshold (DAT), electroretinogram (ERG), multifocal ERG (mfERG)
Sensation & Perception
Topical Blog 4: Peripheral Vision
2/4/2015
For this week’s topical blog post, I chose to learn more about peripheral vision. While reading the chapter, I got kind of lost on the information about peripheral vision and how it works, so I decided to find some other sources to help me understand it better. In chapter 3, we learn how our eyes interpret the visual world in terms of “stripes” created by varying frequency sinusoidal waves. The phase of a particular wave and where it lands on a given ganglion cell determines the cells response, but together we perceive an image of stripes. The chapter explains the biggest challenge to the periphery being visual crowding, or the jumbling of visual information in the periphery. Unable to distinguish objects that are ordinarily recognized easily, we are almost completely unable to ascertain any information from the periphery without redirecting our attention. The spatial ranking strategy dictates the priority and sequence with which our focus moves from central field to the periphery. Although less capacity is devoted to peripheral vision, overall performance is improved.
Peripheral vision is often studied by blocking a portion of the image or video from the central or peripheral field. Direction of gaze and eye movement are then measured to indicate where the individual’s attention is focused on. Because either the central or the surrounding imagery has been covered, it can be determined whether a subject in that area of the visual field was noticed or focused on. Collectively, these studies are referred to as gaze-contingent. In gaze-contingent studies, the visual information is normally blurred rather than left opaque. Strangely, this is based on the assumption that a blurred object in the peripheral field requires less response than does an attention-redirecting one. This assumption has not been empirically substantiated, however. It is interesting that such studies should be based on assumptions that do not have a scientific foundation.
Despite this, researchers have found that blurrier images, or visual information that is otherwise more difficult to understand, does not impact one’s ability to perceive objects in the periphery. In order to shed more light on the function of the periphery in perception, studies have been conducted on individuals with central vision loss. This effectively controls the central vs. peripheral vision in both groups – the group with normal vision reveal how perception relies on both to construct the images we see, the group with central vision loss reflecting the imagery perceived based only on visual information from the periphery.
In one particular case studying broad scene categorization, a group of individuals with age-related macular degeneration were used, so it can be assumed these individuals had normal eyesight for the majority of their lifespan. This reveals something about the function the brain plays in perception. These individuals can no longer see in the center of the visual field, however they, as have the control group of individuals with normal vision, have built up a large bank of information available for recognizing and making inferences. Unfortunately, the results of the study suggest individuals with AMD will have more trouble with scene recognition due to the loss of central vision, and they will not develop better periphery vision as a result of their condition. As we learned in the book, cones are cells mostly responsible for color perception and highly concentrated in the center of the fovea. On the other hand, the primary purpose of rod cells is for less intense light and in higher concentrated in the edge of the retina. As such, individuals with AMD are less able to utilize colors in scene categorization.
Terms: Periphery, frequency, sinusoidal wave, gaze, ganglion cell, visual crowding, spatial ranking strategy, capacity, eye movement, attention, gaze-contingent studies,
http://psycnet.apa.org/journals/xhp/41/1/167.pdf
Explores the role of blur in processing visual information and the effect it has on overall performance.
http://www.sciencedirect.com/science/article/pii/S0042698914000510
This study compares groups with normal vision to AMD to understand more about peripheral vision and its role in scene categorization.
http://ejournals.ebsco.com/Direct.asp?AccessToken=6VXV9LC893XLZNVKCF33KNJKF2OZ8CH9F9&Show=Object
Explains spatial ranking strategy and the tradeoff between peripheral vision accuracy and overall performance.
1A) the topic i found interesting was Visual crowding.
1B) visual crowding relates to the chapter in ways that our brain can only detect and pick apart so much of what we see. visual crowding is where we know what is in front of us but there is so much of it we cant focus on just one object and isolate it.
1C) im interested in it because of how often we are driving down the road and we know everything we see but cant figure out every detail until we get closer. seeing is not always believing, that's something the book has stated and I connect to that. you cant understand something by just one glance you have to give it time.
no one likes a mess even messy people don't like mess I should I'm one such person. I cant keep organized and a clean room for more then a week. When ever that happens you cant find anything and your always tripping over things trying to find your way. I see visual crowding like that that its a mess and you can't find your way through. You see and recognize the objects around you but you can make heads or tails of the mess. our brains see thins mess and just through it all together and hope to figure it out with more detail in a different way. crowding sets limits for our eyes. Each part of our vision can be impaired to do it. weather we want it to our not. Sensation and perception are just two topics of vision and when you start picking them apart they are quite broad. when visual crowding comes into play your sensation and perception are affected and you have to learn to figure out how to decipher the information. its a bottle knack that can limit our vision if we let it
Visual Crowding: a fundamental limit on conscious perception and object recognition
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3070834/
Crowding—An essential bottleneck for object recognition: A mini-review
http://www.sciencedirect.com/science/article/pii/S0042698907005561
Off with your glasses: Visual crowding linked to retina, brain processing
http://www.sciencedaily.com/releases/2014/03/140304141848.htm
visual crowding, sensation, seeing, preception, information,
Visual crowding is called a limit on our visual perception and object recognition and is a decline in visual acuity in peripheral vision because of clutter. It is a serious hindrance for all everyday tasks, including reading, driving and interacting with the environment. The research has implications for patients with macular degeneration, amblyopia and dyslexia. Recent work is helping to establish diagnostic criteria for crowding as opposed to other effects on vision. There is a growing consensus for a two-stage model of crowding involving 1)detection; and, 2)integration or interpretation. Crowding is called a bottleneck to object recognition. Interestingly, visual crowding interferes with facial recognition. New studies hope to help the vision of people who rely on reading glasses.
Terms: macular degeneration, detection, integration or interpretation, object recognition, amblyopia and dyslexia