Period Of Susceptibility In Kittens

Fig. __ Feed-forward projections from the eyes to the brain and topographic mapping. In each eye the visual field on the left and right of the fovea (the cut goes right through the fovea!) projects to different cortical hemispheres: the ipsilateral retina projects to the ipsilateral visual cortex, and the contralateral retina crosses the contralateral cortex (hemifield crossing in the optic chiasma). The first synapse of the retinal ganglion cells is in the lateral geniculate nucleus (LGN), but information from the left (L) and right (R) eye remains strictly separated. The LGN consists of six layers, layers 1 and 2 are primarily occupied by the magnocellular pathway, and 3–6 by the parvocellular. Information from both eyes comes first together

For many years, scientists discovered that the animal kingdom have an incredible diversity of vision. “For example, the bee’s eye produces neural image very similar to that of the human eye but with much worse resolution.” (Nilsson, 1989, p. 298). In addition, Nilsson (1989) shows that the bee’s eyes also detect “polarization of light in the sky and provides color information” (p. 298). Nilsson’s (1989) stated that the primary purpose of an image-forming apparatus in the eye is to

A review of this concept done by Alan Cowey and Petra Stoerig looks at blindsight from a different point of view by first looking at the retinal ganglion cells which receive the visual information from photoreceptors in the eye. They then looked at the particular retinal ganglion cells in a normal retina versus those in a subject with striate cortex damage. The major factors included the amount of degeneration in the retinal ganglion cells and how many remained. The ultimate conclusion came that although there was much degeneration in the cells occurred, there were still some that survived. So what happens with these remaining cells? To try and answer this question they take a look at the ganglion cells in monkeys and see if there is any possible connection from those to the visual cortex that could be causing the phenomenon of blindsight. Cowey and Stoerig discuss the idea of having some other pathways from the ganglion cells to other areas of the brain such as V4, despite the damage of the dLGN that is causing the response to

Phase one: clinically occult changes occur to the circuitry of the neural retina in early stages.

This paper considers that focused primarily on human iris. This choice of this topic was made due to interest of wanting to provide knowledge about the factors that determine eye color. I know, like hair or skin, brown eyes are dominant over blue eye genes. I also know that a person can be identified by the retina scanners because everyone has their iris with unique structural patterns.

Cat eye syndrome is a very interesting chromosomal disorder. At first glance, people may even think it cool and wish that they had it. Cat eye syndrome’s main distinguishing feature is that it makes the eye resemble that of a cat. But cat eye syndrome is much more than just having a cat’s eye, there are many other symptoms, some people have mild cases while other have more severe symptoms. One of the most famous symptoms is ocular coloboma also known as the cat eye. During development of someone with cat eye syndrome or CES, the patient’s eye tissue isn’t fully developed so it causes a gap usually in the iris. For someone with CES, this makes the iris look a bit like a keyhole

In 2002, Slotnick et al. (2002) determine the retinotopic organization of a patient with congenital dysgenesis and normal visual function. The subject was a 32 year old left handed woman with hemispheric cerebral dysgenesis. She underwent a partial right lobectomy at age 30 for treatment of medically intractable seizes. Detailed perimetry mapping within the central 60º of the visual field revealed normal visual function. The findings show that the retinotopic map of the upper right visual field on the ventral left hemisphere was largely normal in both location and organization, but the retinotopic map of the lower right visual field on the dorsal left hemisphere was shifted in location relative to normal. The most focal aspect of the patient’s

Growing up we use our key senses to understand and live in the world around us. After birth newborns eyes are still developing and cannot make out fine details far away. Newborns vision is around 20/240, but by 6 months their vision clears up to around 20/40. At birth infants are genetically programmed to know who their mother is and by three months they can match voices with their gender and ethnic groups. Along with being better to distinguish voices, newborns sense of colors also enhances with age. Perceptual vision is very important for infant eye development. This is necessary because without this ability they would see an “object at a different distance or in a different orientation, they would perceive it as a different object” (Santrock 161). There are two main factors for this size constancy,

When the retina is cultured in vitro, some condition, such as timing and dosage is easier to manipulate than that in vivo. In this experiment, retinae from newborn pups are dissected, flattened, and cultured in vitro with neural basal media. Shh signaling agonist (purmorphamine) will be added at different concentrations or at different stages of development (P3, P5, P8, etc.). Retina is harvested at P10 and the proportion of cone/off bipolar cells is determined. As the animal also express ON-type bipolar cell marker, this experiment allows us to determine the proportion of ON/OFF bipolar cells. This experiment may bring the research to the next stage where the function of Shh signaling in ON/OFF bipolar cells development will be further

One scenes that develops in a growing child is sight. Sight is created by an electric signal that travels through optic nerves to the lamus in the brain when the eye sees light and focuses it to the retina. These signals stimulate different parts of the

It is understood that large differences in prescriptions between both eyes, and abnormally high prescriptions in both eyes in early development can contribute to amblyopia. However, in this study the experimental monkeys had a normal range of refractive error in early development, and none developed anisometropia during this time. It was also noted that there was no relationship between the depth of amblyopia and the refractive error of the subjects in early infancy.

The visual cortex is also referred to as the striate cortex due to the line of Gennari, which is stripes of axons from the lateral geniculate body. These axons are referred to as ocular dominance columns. These columns respond to light input preferentially from one eye over the other eye. These columns are important for binocular vision, or the use of both eyes for vision. This finding and the discovery of ocular dominance columns teaches us that the brain exhibits cortical plasticity, or the ability of the brain to change over the course of an individual's lifetime. It was discovered that monocular deprivation (deprivation of one eye for an extended period of time) resulted in degradation of ocular dominance columns and the non-deprived eye

The eye starts to develope at about 16 weeks of pregnancy. Retinopathy prematurity effects prematre infants weighing about 2.75 pounds or born before 31 weeks of gestation. Retinopathy effects both eyes in infants. Cause is from abnormal blood vessel growth spreading throughout the retina and the tissue that lines the back of the eye. The vessels leak and are fragile causing scarring of the retina and pulling the retina out of position causing retinal detachment. In premature infants the blood vessels have reached the edges of the retina and normal vessels growth stop's.

Normal vision occurs by a coordinated synthesis of the retinal images into a single brain image. If, however, one of the eyes does not transmit a coordinated or useful image the brain may choose to ignore this image when conducting its synthesis. The region of the

In 1981, D.H Hubel and T.N Wiesel were awarded half of the Nobel prize in Physiology or Medicine, along with R.W. Sperry who received the other half. The two had been conducting experiments and publishing their findings together for over twenty years, before they were awarded the Nobel prize for “their discoveries concerning information processing in the visual system.” They produced many reports including single and complex cells, and ocular dominance. Their work provided better understanding of the visual system and therefore led the way for others to develop knowledge and treatment of eye conditions. Their discovery also helped other scientists to conduct and publish work of their own.