Milena Canning has a bizarre condition called Riddoch syndrome. Technically, Canning is blind but unlike most people who experience total blindness, she occasionally catches sight of objects – provided they are moving, that is.
A team of neuroscientists at Western University’s Brain and Mind Institute explain this extraordinary case in the journal Neuropsychologia.
Canning, 48 and from Scotland, lost her vision 18 years ago after she woke up from an eight-week coma triggered by a respiratory infection and a run of strokes. Months later, a green glimmer caught her eye. It was a sparkly green gift bag.
Every now and then, she would catch sight of other objects – rain trickling down a window pane, water running down a drain, steam drifting up from a cup of coffee, her daughter’s hair tie bouncing along as she moved. But these were just glimpses and while she could just make out her daughter’s hair tie, her daughter’s face remained obscured.
To work out what exactly is going on here, researchers at the Brain and Mind Institute in London, Canada, used MRI and other tests to analyze the real-time workings of Canning’s brain. The images revealed an apple-sized crater of missing tissue at the back of her brain, where the occipital lobes (the brain’s visual processing center) should have been.
“In Milena’s case, we think the ‘super-highway’ for the visual system reached a dead end,” lead neuroscientist Jody Culham, a professor in the Department of Psychology and Graduate Program in Neuroscience at Western, said in a statement.
“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.”
The researchers had Canning intercept and grab balls being rolled towards her. Her ability to recognize the color of the balls was inconsistent but she was able to perceive motion, speed, size, and direction (as you can see in the video below). And while she was able to maneuver around chairs, she was only able to tell if the hand in front of her was a thumbs up or thumbs down half the time, which is exactly what it should be if left to chance.
“This work may be the richest characterization ever conducted of a single patient’s visual system,” Culham added.
As for Canning, “I can’t see like normal people see or like I used to see,” she said. “The things I’m seeing are really strange. There is something happening and my brain is trying to rewire itself or trying different pathways.”
Not only does this research suggest that traditional ideas of what is considered “blind” are overly simplified, it shows just how malleable the brain is and how incredible it can be at healing itself.
Western University’s Brain and Mind Institute