Funded Grants

Learning to see in late childhood

The Problem and a Unique Opportunity
Understanding how the human visual system learns to perceive objects in the environment is one of the fundamental challenges in neuroscience. Through experience, the brain comes to be able to parse complex visual scenes into distinct meaningful objects. Several questions about this process remain unanswered. How much visual experience is needed for the development of this ability? What are the intermediate stages in the evolution of the object representations? How critical is early visual experience for the development of object perception?

There are two dominant approaches for studying these questions: 1. experimentation with infants, and 2. experiments with adults using novel objects. These approaches have yielded valuable results, but also have some limitations. For instance, infant experiments are operationally difficult due to subjects’ distractibility and limited response repertoire. Experiments with adults, on the other hand, cannot sidestep subjects' prior visual experience, even though the objects used as stimuli may be novel.

We have identified a unique population of children in India that allows us to adopt a very different approach. India is home to the world's largest population of blind children, many of whom have treatable blindness. Poverty, ignorance and lack of simple diagnostic tools in rural areas deprive these children of the chance of early treatment, and severely compromise their chances of having an education, a career and, indeed, normal odds of survival. Such a population does not exist in developed countries such as the United States. Given the extensive network of neonatal clinics and pediatric care in developed nations, cases of curable blindness are invariably treated within a few weeks after their discovery and it is, therefore, rare to find an untreated case of blindness in a child of more than a few months of age. In India on the other hand, many curably blind children spend several years, or even their entire lives, without sight.

We propose to work with a few selected hospitals in India to launch outreach programs that can identify children in need of treatment and provide corrective surgeries. In undertaking this initiative, we will not only be addressing a pressing humanitarian need, but will also have the opportunity to observe the time-course of development of visual skills after sight onset. The results promise to yield insights into fundamental questions regarding object concept learning and brain plasticity. We have named this effort ‘Project Prakash’ after the Sanskrit word for light.

The Scientific Goals of the Project
Using a battery of behavioral tests, we shall longitudinally characterize the unfolding of different visual skills in order to discern any causal dependencies between them and thus understand the ‘bootstrapping’ mechanisms of vision. Additionally, using functional brain imaging, we shall examine changes in cortical organization as a function of time post-treatment. The behavioral and imaging data together promise to provide a unique window into the time-course and neural correlates of visual learning. They will also allow us to infer how the mechanisms of learning are influenced by visual deprivation during early, perhaps ‘critical’, periods in the life-span.

The Broader Significance of the Project
Besides providing novel insights regarding basic questions in experimental and theoretical neuroscience, this project also promises to yield more pragmatic benefits.

Ophthalmic care for a broader spectrum of children: Children in economically strong urban families in India have access to excellent ophthalmic care. New Delhi alone is estimated to have over 1,200 ophthalmologists. However, many poor families, especially those in rural communities lack such access. The outreach efforts of our project will allow us to bring the benefits of modern medicine to several of these communities.

Development of effective rehabilitation strategies: Our understanding of the consequences of visual deprivation during childhood on subsequent brain development is, at present, extremely limited. Studies conducted several decades ago to explore the effects of impoverished stimulation on animals are still our primary sources of reference on this issue. However, we cannot be certain how applicable the predictions of these studies are for human children and, of course, it is difficult to assess cognitive functions in animals. This issue is of great significance for child health. As new eye-treatments become available and existing treatments reach children who are currently blind, a basic question we have to confront is how to proceed with their integration into the sighted world. In this context, Project Prakash holds the potential for making a significant impact by directly assessing how extended visual deprivation influences children’s subsequent development of visual skills. This undertaking is a pre-requisite for developing rehabilitation strategies to compensate for particular deficits.

Understanding mental health implications of childhood blindness: Past case studies, such as those compiled by von Senden (Space and Sight, 1960) indicate that extended visual deprivation can have a significant impact on an individual’s long-term mental health. A potential contributing factor is the difficulty patients face soon after sight onset in performing complex visual tasks, such as face processing, and the sense of falling short of their own and other's performance expectations. Project Prakash can help mitigate this problem by helping identify key visual impairments following treatment and providing guidelines for pre/post-operative counseling and for designing techniques that can compensate for these deficits.

Enhancing social acceptability and awareness of childhood blindness: India has an incidence of childhood blindness that is amongst the highest in the world. Yet, in the Indian society, this disorder carries grave stigmas and is poorly understood by the population at large, leading to superstitions, dangerous non-medical 'remedies', or, often, no treatment at all for the affected children. A beneficial consequence of conducting this project in India is to increase awareness regarding this condition and the available treatment options. The project will help the children by removing misconceptions from their parents' minds and inducing them to seek proper treatment for their children. Furthermore, by highlighting the problem of childhood blindness in prominent international forums and journals, the project may catalyze the formulation and launch of additional initiatives by philanthropic and government agencies for countering the problem of childhood blindness, both in India and other countries.

Facilitating education: Since cases of sight restoration after prolonged blindness are of natural interest to scientists and lay people alike, the reports, audio/visual material and papers resulting from this work serve as effective conduits of information regarding basic issues in visual neuroscience. The project directly enhances the education of the undergraduate, graduate and post-doctoral students involved in the design and running of the experimental studies. We also plan to disseminate the findings of this project via special symposia that will be open to other scientists working in this field as well as to the public at large.