Sense and Lens

When those born blind get their vision, they have difficulty correlating the real to the ‘felt’. T.V. Jayan on the outcome of a project for visually challenged children in rural India.

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The participants were asked to feel a building block and then match the object felt with two blocks, one square and the other circular.

Blind children from India’s hinterland have found themselves a place in history by helping researchers resolve a profound and long-standing problem that perplexed philosophers and neuroscientists for over three centuries.

Posed for the first time in 1688 by Irish scientist and politician William Molyneux, the question is elegantly simple: can a person who has been blind from birth but gained sight in adulthood visually discriminate between objects that were previously identifiable only by touch?

The answer seems to be a definite “no”. That’s the conclusion of a team of Indian and American scientists after their studies involving blind children in rural India whose eyesight was restored surgically. In other words, a person’s ability to learn the correspondence between how an object looks and how it feels is not innate; it needs to be learnt. The study appeared yesterday in Nature Neuroscience.

 

The five children, aged between eight and 17, who participated in the study are part of a project launched by Pawan Sinha, a brain and cognitive sciences professor at the Massachusetts Institute of Technology (MIT), the US.

The Molyneux question has been the subject of much debate in philosophy and neuroscience over the past three centuries, says MIT’s Richard Held, the first author of the paper. It’s important for two reasons, he says. Philosophically speaking, it touches upon the core of the “nature versus nurture” debate. It also addresses a deep scientific question: do the various senses of a living organism share an innate common space?

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Though efforts to answer the question began not long after it was first posed, it had thus far remained unresolved. The primary reason for this is that in the West, a majority of curable congenital blindness cases are detected in infancy and treated as early as possible. But the scientists working with Project Prakash — which Sinha launched in 2004 — however, had an opportunity to take a fresh look at the problem. They had been working with children with vision disabilities in rural India as part of the humanitarian venture. The country is said to have the highest number of blind children in the world — more than one million.

Most cases of blindness in India are caused by vitamin A deficiency, cataracts, retinal or optical dystrophies, or microphthalmos (poorly developed eyes). About half the cases are treatable or preventable, but many never receive medical care, especially in rural areas.

Under the project, the scientists have so far screened more than 20,000 children in some of the most backward villages in Uttar Pradesh, Haryana, Rajasthan and Madhya Pradesh. “Over 700 children have been treated for conditions ranging from severe refractive error to congenital blindness,” says Sinha, a co-author of the study. The medical care was provided at New Delhi’s eye hospital, Shroff’s Charity Eye Hospital, a project partner.

For their study, the scientists chose five children who were blind from birth owing to a congenital cataract or an opaque cornea. After surgery — a cataract removal or a corneal transplant — the participants were asked to feel a building block and then match the object felt with one or two blocks (of two different shapes — one square and the other circular). The children were unable to match the blocks they felt with what they only saw. Significantly, their performance improved substantially five days later, although they didn’t receive any kind of training.

This rapid improvement was surprising, says Yuri Ostrovsky, another MIT researcher associated with the study. He points out that many visual tasks, such as face perception, can take six to 12 months to learn after sight is restored. “The outcome has been a surprise — one that has important implications for theories regarding how the brain learns to acquire a coherent account of the complex environment,” Held told KnowHow.

Sinha, who holds a BTech from the Indian Institute of Technology, Delhi, says the project has been an eye opener in more ways than one. It served a dual purpose: providing sight to blind children and advancing fundamental science. This, along with earlier findings from Project Prakash, shows that the human brain retains an impressive ability to launch programmes of visual learning well after the normal period of their deployment has passed.

“It has helped clear several myths regarding vision. Most eye doctors hesitate to treat older patients because they believe the brain is incapable of learning to see after age six or seven,” Sinha told KnowHow. “Our work has broken this dogma.”

The results of the study are significant for basic neuroscience as well as paediatric ophthalmology and implementation of later-stage blindness treatment programmes.

Here’s hoping there will be light for all.
You may click to see :Those Who Once Were Blind Can Learn To See, Study Shows

Source: The Telegraph ( Kolkata, India)

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