7-Year-Old Who Lost Most of His Visual Cortex Stuns Doctors with Remarkable Vision
The brain is one region of the body whose function and behavior is still largely an unfolding mystery. One proof of this is a recently shared case of a seven-year-old Australian boy who, despite missing the majority of his visual cortex, is baffling doctors with his ability to recognize faces and even play soccer.
The first case of its kind
The team of researchers based at the Australian Regenerative Medicine Institute at Monash University and documenting the experiences of the little boy whom they’ve named “B.I.”—the first case of its kind—presented the case study to a group of their peers this week at the annual Australasian Neuroscience Conference, which was held in Sydney.
B.I. had lost his primary visual cortex at just two weeks due to a brain injury affecting his bilateral occipital lobe, the lobe which is responsible for coordinating vision. Add to this is his diagnosis at birth with a rare metabolic disorder known as medium-chain acyl-Co-A dehydrogenase deficiency (MCADD), an inherited metabolic disease which stops tissues from turning certain fats into energy. This meant a lesion in B.I.’s primary visual cortex (V1), which theoretically should affect his ability to convert retinal information into a clear image. The visual cortex is located in the outer region of the brain—a part of the cerebral cortex measuring only 1.5 to 2mm—that plays the important role of processing visual information.
In other words the little boy, it seems, has two significant medical strikes against him. The condition he should suffer from is known as blindsight, a strange medical outcome which means that one can see but has no consciousness of the images. The team noted how, despite the damage suffered to the brain, that B.I. showed signs of only being slightly near-sighted. Monash University neuroscientist and presenter Iñaki-Carril Mundiñano commented on the remarkable nature of the case: “You wouldn’t think he is blind,” he says, adding, “He navigates his way around without any problems and plays soccer and video games.”
“Despite the extensive bilateral occipital cortical damage, B.I. has extensive conscious visual abilities, is not blind, and can use vision to navigate his environment,” the team noted in their study, titled More than blindsight: Case report of a child with extraordinary visual capacity following perinatal bilateral occipital lobe injury”, which appeared in last month’s Neuropsychologia (Epub ahead of print).
Mundiñano also noted that the scans done of B.I.’s brain revealed a larger concentration of neural fibers in two areas located towards the back of the brain, close to the visual cortex: the middle temporal area and pulvinar. The first aids with motion detection, while the second is involved with the control of sensory signals. The boy’s incredible recovery is an example of neuroplasticity, a term used to describe a self-repairing and self-adjusting mechanism carried out by the neurons in the brain in order to compensate for an injury.
"Furthermore, he can readily and consciously identify happy and neutral faces and colors, tasks associated with ventral stream processing," says Mundiñano optimistically.
Via: New Scientist, NIH, BBC, ANS
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