The Art of Seeing Without Sight
29 January 2005
IT IS an odd sight. A middle-aged man, fully reclined, drawing pictures of hammers and mugs and animal figurines on a special clipboard, which is balanced precariously on a pillow atop his ample stomach.
A half-dozen people buzz around him. One adjusts a towel under his neck to make him more comfortable, another wields a stopwatch and chants instructions to start doing this or stop doing that, and yet another translates everything into Turkish. A small group convenes in a corner to assess the proceedings. A few of us just stand around watching, and trying not to get in the way. The elaborate ritual is a practice run for an upcoming brain scan and the researchers want to get everything just right. Meanwhile, the man at the centre of all this attention, a blind painter, cracks jokes that keep everyone tittering.
The painter is Esref Armagan. And he is here in Boston to see if a peek inside his brain can explain how a man who has never seen can paint pictures that the sighted easily recognise - and even admire. He paints houses and mountains and lakes and faces and butterflies, but he's never seen any of these things. He depicts colour, shadow and perspective, but it is not clear how he could have witnessed these things either. How does he do it?
Because if Armagan can represent images in the same way a sighted person can, it raises big questions not only about how our brains construct mental images, but also about the role those images play in seeing. Do we build up mental images using just our eyes or do other senses contribute too? How much can congenitally blind people really understand about space and the layout of objects within it? How much "seeing" does a blind person actually do?
Armagan was born 51 years ago in one of Istanbul's poorer neighbourhoods. One of his eyes failed to develop beyond a rudimentary bud, the other is stunted and scarred. It is impossible to know if he had some vision as an infant, but he certainly never saw normally and his brain detects no light now. Few of the children in his neighbourhood were formally educated, and like them, he spent his early years playing in the streets. But Armagan's blindness isolated him, and to pass the time, he turned to drawing. At first he just scratched in the dirt. But by age 6 he was using pencil and paper. At 18 he started painting with his fingers, first on paper, then on canvas with oils. At age 42 he discovered fast-drying acrylics....cont'd
http://www.newscientist.com/channel/being-human/mg18524841.700......................
Seeing Without Light
Knowledge does not come to us in details, but in flashes of LIGHT from heaven. ~ Henry David Thoreau
Cells see the light with melanopsin
Creation of light-sensitive cells could lead to treatments for blindness.
Thanks to the rod and cone cells in our eyes, our brains can use light to build images. Recent studies identified a third type of cell that responds to light and dark. Three research groups have now confirmed that melanopsin is the pigment that this cell-type uses, opening possible avenues for treating blind people.
In the classic model, mammals have two types of light-detecting cells, called photoreceptors, in the retina at the back of their eye. Rod cells use the rhodopsin pigment to pick up dim light, and cone cells use related pigments to discriminate colour.
But three years ago, scientists found a third type of light-sensitive cell. In such cells, a pigment called melanopsin is used to tell night from day. But apparently the visual parts of the brain do not use this information. Instead, these cells communicate with the neurons at the base of the brain that set the daily body cycle.
For example, mice without working rods or cones cannot see images. But researchers showed that they can still use a small set of melanopsin-containing cells in the retina to adjust their biological clocks. Exactly how melanopsin worked, however, remained a mystery.
..cont'd
http://www.nature.com/news/2005/050124/full/050124-13.html