Toronto June 13 (IANS) In an extremely rare case neuroscientists have mapped the brain of a Scottish woman who is blind but has developed the remarkable ability to see objects in motion an advance that reveals how visual and cognitive functions go together.
Milena Canning a 48-year-old Scottish woman lost her sight 18 years ago after a respiratory infection and series of strokes.
Months after emerging blind from an eight-week coma she was surprised to see the glint of a sparkly gift bag like a flash of green lightning.
To understand her unique vision scientists at the Western University s Brain and Mind Institute in Canada conducted tests including functional Magnetic Resonance Imaging (fMRI) to examine the real-time structure and workings of her brain.
They determined that Canning has a rare phenomenon called Riddoch syndrome -- in which a blind person can consciously see a moving object but not if its stationary.
"She is missing a piece of brain tissue about the size of an apple at the back of her brain - almost her entire occipital lobes which process vision " said neuropsychologist Jody Culham Professor at the varsity.
"In Canning s case we think the super-highway for the visual system reached a dead end.
"But rather than shutting down her whole visual system she developed some back roads that could bypass the superhighway to bring some vision -- especially motion -- to other parts of the brain " Culham said in a paper published in the journal Neuropsychologia.
In essence Canning s brain is taking unexpected unconventional detours around damaged pathways.
The researchers found that Canning was able to recognise the motion direction size and speed of balls rolled towards her; and to command her hand to open intercept and grab them at exactly the right time. She could also navigate around chairs.
Yet she inconsistently identified an object s colour and was able only half the time to detect whether someone s hand in front of her showed thumbs-up or thumbs-down.
"I can t see like normal people see or like I used to see. The things I m seeing are really strange. There is something happening and my brain is trying to rewire itself or trying different pathways " Canning said.
The research shows the remarkable plasticity of the human brain in finding work-arounds after catastrophic injuries suggesting conventional definitions of "sight" and "blindness" are fuzzier than previously believed.

--IANS rt/mag/bg