Indian-born 'scientist couple' knows what let humans read texts, recognise faces?

Indian-born scientist couple has found a special spot in eyes called 'fovea' which plays an important role in humans to focus on TV screens and also read, a unique ability that is found in Homo sapiens.

The research describes the mechanism that let humans read texts, recognise faces, enjoy colors, say the scientists.

Kolkata-born Raunak Sinha and Mrinalini Hoon, a 'scientist couple' who push the frontiers of neuroscience to better understand vision.

Sinha says this "recent breakthrough in understanding how the most important aspects of our vision works at a cellular level. This work illustrates the physiological basis of how our central vision, mediated by the region in the eye called fovea, works at a cellular level and how it differs in its operation from the region that mediates our peripheral vision".

Scientists have revealed some reasons behind the unusual perceptual properties of the eye's fovea’. Only humans and other primates have this dimple-like structure in their retinas.

Also Owls and other predatory birds, and some reptiles have a similar structure. The fovea is behind our colorful visual experiences.

"Diseases such as macular degeneration are much more debilitating than deficits in peripheral eyesight because of the importance of the fovea to everyday vision," says Sinha of the Department of Physiology and Biophysics at the University of Washington's, School of Medicine.

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Explaining ‘fovea’ he said that it is ‘’a specialised region that dominates our visual perception and provides more than half of the input from the eyes to the visual cortex of the brain.”

"When you look at a scene an arm's length away," he says, "the fovea subtends a field only about the size of your thumbnail. Our eyes undergo rapid movements to direct the fovea to various parts of the scene."

The absence of a fovea in most mammals, he says, and technical challenges associated with recording from the primate fovea, led to a paucity of information about how the fovea operates at the level of cellular circuits.

Using high techniques, Sinha helped lead a study that revealed that the computational architecture and basic visual processing of the fovea are different from other regions of retina.

“The results help explain why central and peripheral vision have different qualities,” he says.

The fovea is best for fine tasks like reading and its located near optic nerve.

“This low sensitivity is what makes us see motion in flipbooks and movies. It's also what prevents us from seeing flicker when a computer or TV screen refreshes, unless we glance at the screen (especially the old-fashioned CRT monitors) from the corner of our eye,” explains the Kolkata- born scientist.