NEW Delhi- Manoj Kumar Yadav came into this world with cataracts. In developed countries, a simple surgery heals this disabling eye disease in the first months of life. But as the vast majority of people in India, Yadav was born in a village, with limited access to health care. His parents are poor and uneducated. They do not even realize their infant son was blind until he starts banging crawling. Years later, when regional doctors examined Yadav, they told him he would never see. "We have given up," recalls Yadav, now 22. "We thought it was useless to run over trying to find a cure."
Then, in 2011, a team of specialists to New Delhi Yadav visited village in Uttar Pradesh. They he and other blind children examined and kindled hope that Yadav could one day be able to see after all. This August, he and his father took a train trip 13 hours in the capital of India. Here at the Hospital Dr Shroff Charity Eye, a surgeon excised his cataract lenses mounted and slid in synthetic for them.
When doctors removed the bandages a day later, the world Yadav was filled with light, and shapes that were impenetrable to him. He could not tell people objects, or if something has ended and another began. His brain, private information of his eyes for 18 years, did not know what to do with the flood of visual stimuli. But over the next few months, his brain gradually learned to interpret the signals he was getting from his eyes, and blurred and confused world began to come into focus.
Yadav is among hundreds of blind children, adolescents, and young adults who are now able to see through a project called Prakash, which means "light" in Sanskrit. India may have the largest number of blind children in the world. Estimates range from 360,000 to nearly 1.2 million. The vast majority live in rural areas, their quality of life worsened by poverty, lack of access to health care, and a lack of facilities for the disabled. Almost 40% of these children are considered preventable or curable blindness, caused by congenital cataracts, damaged corneas, and eye infections.
Led by neuroscientist Pawan Sinha, Prakash project began in 04 as a humanitarian effort to address this problem. But there was also a scientific purpose. Sinha, based at the Massachusetts Institute of Technology in Cambridge, speculated that the newly observed children could help answer a question that had long intrigued him: How the brain learns to see? Initially funded by the US National Institutes of Health as an exploratory grant, Prakash has since become a revolutionary effort in neuroscience. For years, doctors assumed that once a blind person passed a critical age in infancy, without vision, their brain would never be able to make sense of the visual world. With patients like Yadav, Prakash demolished this hypothesis.
Mr. Atarod / SCIENCE 
"It took me years about a year and a half before I could see everything clearly," said Yadav. Light and short Yadav is polite and soft-spoken, his eyes darting nervously back and forth. The condition, nystagmus, is a relic of his congenital blindness. But disappeared with the cataracts, it does not stop to see. "Now I can even ride a bicycle through a crowded market," he said.
Prakash "beautifully demonstrates that there is still room for plasticity and recovery" in patients who have grown blind, said Collignon, a neuroscientist at the University of Trento in Italy. This does not mean the new psychic will be able to see as well as those born seers, he warns. "Not supported by the data."
Yet the surprising ability of Prakash patients to obtain an important vision is rewriting visual neuroscience. As the medical gain their efforts became clear, the project leaders have launched a series of studies, low-tech patient responses tests to visual illusions functional MRI (fMRI) imaging of their brain reorganization in response to visual input. While the survey how the newly preview process visual cues, project scientists are peeling away layers of mystery about aspects of the view that come pre-programmed and are shaped by experience.
OPHTHALMOLOGY MANUALS have long suggested that trying to give sight to adolescents who have been blind from birth is unlikely to succeed. In a series of groundbreaking studies in cats and monkeys who won the Nobel Prize in Physiology or Medicine in 1981, Torsten Wiesel and David Hubel have shown that if the brain is deprived of visual signals during a critical period shortly after the birth, vision is impaired for life. There was no similar experiments in humans for ethical reasons, but scientists took our slams critics windows closed between 6 and 8. This belief guided surgeons Shroff, who turned away the blind children over 8 years.
However, Sinha unearthed some studies it decades ago that suggested congenitally blind adults could earn at least some vision after cataract surgery. Then in 02 and 03, while traveling across India to understand the extent and causes of blindness, Sinha met four people who all had cataracts removed as teenagers and had gained some vision. Anecdotal evidence was enough to convince Sinha that, given recent advances in medicine, Prakash project was worth pursuing, and it convinced the Shroff surgeons to give it a try.
The eye specialists and team of health workers set up screening camps in rural areas to identify children who might benefit from surgery and nonsurgical interventions such as eyeglasses, drops eyes, and medications. So far, more than 1,400 children received nonsurgical care and nearly 500 children and young adults have undergone cataract surgery. About half of these patients-those that scientists believe blind research topics-birth became.
Their recent studies show that the experience is not critical for certain visual functions. Instead, the brain seems to be wired to interpret at least some simple aspects of the visual world. The evidence comes from tests of visual illusions that also help settle a longstanding debate about why the brain misinterprets particular types of images.
When our perception of an image differs from reality, we experience a visual illusion. Some neuroscientists believe that the innate wiring of our brain is responsible illusions; others think they are a product of learning. The resolution of this debate has been difficult, said Susana Martinez-Conde, a neuroscientist at the State University of New York Downstate Medical Center who studies delusions. "Babies can not realize the visual experience," she said. "And it would be unethical to deprive a baby of visual experience to test." The answer was "anybody's guess," said up Prakash this project began studying newly observed children whose vision it at the first acquisition, is close to.
in 2010 and 2011, the team Sinha took newborn nine children of those about to undergo surgery for cataracts. the subjects had been blind since birth, according to parents and surgeons Shroff Charity Hospital Eye. Shortly after their bandages were removed, scientists have shown their Ponzo illusion. first shown there is more than a century, this illusion usually involves converging lines on the horizon (such as railroads) and two short parallel lines cut through them. Although the lines horizontal are identical, one near the horizon is more like.
The prevailing explanation of the Ponzo illusion is that it is the result of brain experience interpreting 2D images as 3D scenes, with the individual elements of the images perceived as different depths and distances. "This learning brings us to combine these two identical rows in this illusion as being at two different distances from us," says Sinha. The brain interprets the line closer to the apparent horizon further and thus longer than the other identical line.
functional MRI shows activity in the visual cortex of a newly overview Prakash patient begins to perceive human faces. Prakash children gradually learn to use the same region of the cortex that supports face perception in people normally observed. Project Prakash 
If the Ponzo illusion were the result of visual learning, Prakash children would not fall for it. But to the surprise of the team, the children were equally sensitive to Ponzo illusion as were the control subjects with normal vision. They consistently found the line near the horizon addition, the team reported in Current Biology May
children also fell for the illusion Müller-Lyer, a pair of lines with arrows on both ends; a tip assembly arrowheads outwardly, the other inwardly toward the line. The line with the arrows inwards seems. "All we can say on the basis of these results is that this is not the experience," says Sinha. "It's something else. It is probably driven by very simple factors in the image that the brain is probably naturally programmed to respond to. "
Martinez-Conde is willing to hazard a guess on how the Müller-Lyer illusion works. His previous research has shown that our eyes tend to notice more corners than straights. Maybe be, she said, our brain focuses on the corners arrows outward, making the line between watching shorter than the arrow line inward. "But this should be taken with a large grain of salt because I have no data to prove it. "
Whatever the mechanism, the new study adds to the evidence increasingly" that we are not blank slates when we born, "says Martinez-Conde. other evidence comes from a recent study by Amir Amedi, a neuroscientist at the Hebrew University, and his colleagues in which they have used fMRI to compare the visual cortex congenitally blind individuals with that of those normally observed. They found that the basic organization of the visual cortex of blind people of birth is similar to that of normal vision, and both have similar connections between different parts of the cortex. This means that "we are born with this machinery to see that in a sense does not require visual experience to emerge," said Amedi. "The visual system comes with some connections and means of calculation."
SUCH cabling May HELP children acquire Prakash functional vision in the months following surgery, Amedi speculates. But experience and learning seem to play a more important role in the visual acquisition. "This n 'there is more evidence that [even] adult brain can change in the structure and function, "says Brigitte Roeder, a neuropsychologist at the University of Hamburg in Germany. for example, studies have shown that adults who regularly play video action games are better at certain visual tasks, such as reading the fine print on a bottle of prescription or monitoring several friends who are moving through a crowd.
More relevant to Prakash children is the ability to create a mental image of a 3D space. "Satellite imagery is very important in our lives," said team member Prakash Tapan Gandhi, a neuroscientist at the Indian Institute of Technology, Delhi, New Delhi. "If I ask you, think of your kitchen where you kept that, you can visualize it. This is very important for our daily lives. "But blind people are not able to imagine spaces. When tested for this ability using a die and moving ankles, Prakash children before the poor results of surgery compared with people normally seen, said Gandhi. Few after surgery, however, they begin to get better at spatial imaging tasks. the vision must be crucial to help the brain create mental maps of the areas, he said. and the brain is not no critical window for this ability, or the window remains open until much later in life, Gandhi and colleagues reported in 2014 12 March issue of Psychological Science.
the team . found similar adaptability in the ability to distinguish a human face from pictures facelike Shortly after surgery, Prakash patients can not differentiate it also contradicts the dogma. Homing on the faces is an ability visual scientists think is innate. But after a few weeks, the new seer can recognize a human face and begin to recognize different faces. The team also found that their patients quickly learn to connect contacts view. In other words, they are soon able to recognize objects they have touched blindfolded when they see these remote objects.
But plasticity has its limits. Collignon and his colleagues studied a group of adults in Canada who were born with cataracts, but underwent corrective surgery before turning 1. Despite at least two decades of sight restored, each individual had slightly blurred vision. Their 3D perception and their ability to detect motion has also been compromised, according to unpublished results. The researchers found that the brains of these people seem to be wired differently. Unlike people normally seen, their visual cortexes also sound process, they reported in August in Current Biology
"What is really striking here is that we're talking about people who are deprived [of sight] for a few weeks a few months, but it leads to a reorganization longtime brain to better respond to sound, "says Collignon. Prakash patients who are blind for years, are also likely to have them reorganized visual cortex, he said, which could hamper the recovery. "They have a record of their past [in their brains], and their past is blindness," he said. "These people will never be able to recover the vision as one who has seen before."
The findings from Sinha confirmed. The Prakash patients do not develop a vision as sharp as normally seen others. "Despite following these children for many years, we do not find an increase in the acuity to normal," says Sinha. This suggests a critical window of acuity that closes some time before they turn 8 young age Prakash to this Treaty.
Yadav's experiences are typical. "I can read the headlines with my glasses," he said. But 4 years since his operation, he still has trouble reading the fine print in newspapers and books
The window also appears close early for contrast sensitivity :. The ability to discern contrasts, shades and patterns, one of the most basic functions of vision. In one test, the team of Prakash Sinha shows children four models-a house, a square, an apple, and a circle and asks them to identify patterns as they change size and contrast. Normally sighted people can detect these patterns for a range of sizes, if the contrast is above a certain threshold. Prakash for children, their contrast sensitivity significantly improves until several months after the surgery, but never reached normal levels. They remain blocked in the detection of a limited number of sizes, and only when the contrast is quite high.
Manoj Yadav bicycles to work in Gorakhpur, India. "I can ride a bike, even in a crowded market," he said. Graham Crouch 
Taken together, the results demonstrate that no single critical period governing vision says Amy Kalia, a postdoctoral fellow with Sinha. "is recoverable vision or not," she said, "is a more complex story."
The training could help children recover Prakash most visual function, said Uri Polat, a neuroscientist at the University of Tel Aviv in Israel. "The window did not close," he said. "It becomes less sensitive."
In 04, Polat was the first to show that training can restore vision in adults with amblyopia, or lazy eye. A lazy eye prevents the normal development of the visual cortex in infancy. Patients have a binocular visual impairment and low acuity and contrast sensitivity; the diminished view was considered irreversible after age 10. Patients Polat was watching a computer screen with variations of an image Gabor Patch, who fuzzy patterns in black and white that change size and contrast . After only a month of training, patients had greater acuity and contrast sensitivity.
Amedi agreed that training is the key, but think it should involve touch and sound, too, meaning that blind people rely on to navigate the world. His research showed that her interpreting or touch, they rely on some of their visual cortex normally devoted to vision. For example, they use the same part of the brain that use of sighted Braille for reading. Project Prakash plans to open a boarding school the next year for the rehabilitation and education of children after cataract surgery using physical exercises and multisensory experiences.
FINALLY , the team will reveal how Prakash restore vision changes the visual cortex. They begin to fathom the changes in the brain with fMRI.
When the image of the visual cortex of a patient before and 2 days after surgery, different areas of the cortex appear to work in synchrony. "So if you have high activity in a part of the cortex, you will have a similar activity in another part of the cortex," says Sinha. "It is as if a large part of the visual cortex is pulsating together."
However, only a few months after surgery, fMRI picture begins to change. Different regions of the visual cortex light up differently, suggesting a division of labor. Pictures of human faces presented to patients, for example, activate a zone the cortex known to meet the faces of people normally observed.
"It makes a lot of sense," said Amedi. "When they begin to process visual information, they can not perform tasks. They can not identify an object, a person. It is all the same nonsense for them." But as time passes, and the brain learns to distinguish objects, shapes and faces, different areas of the visual cortex begin to specialize.
Sinha, for one, do not expect these changes in the brain. "I'm amazed by how much, how massive change is and how it happens quickly, and how the end of life, it can happen, "he said. He did not wait for the geyser of project results generated. "I was afraid of having to work with children old enough, we were ourselves up for failure." Instead, the project has brought hundreds of young people like Yadav in light while keeping the field visual neuroscience in a new light well.
See our slide show Project Prakash.
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