Common wisdom says learning disabilities are caused by problems with the way a person’s brain is “wired”. But a new study from Norway indicates that part of the problem may focus on how the eyes work rather than on the brain.
The phrase “learning disabilities” can mean many things. The most common definition is a neurological disorder caused by changes in the way the brain works. Some commonly recognized learning disabilities include:
• Dyslexia – difficulty reading and writing
• Dyscalculia – problems with arithmetic and math concepts
• Dysgraphia – problems writing legibly
• Dyspraxia – problems with motor coordination
The study, by researchers at the Norwegian University of Science and Technology (NTNU), found that the problem in many of these conditions may actually be caused by malfunctions in the eyes, rather than in the brain.
The inside lining of the human eye is called the retina. The retina is made up of many photoreceptor cells. When light enters the eye, these cells gather the images and convert them to electrical impulses that are sent to the brain through the optic nerve. Some of these photoreceptor cells see color while others see shades of gray in dim light. Some are able to focus on fine details and others see a broader picture.
One special set of these photoreceptor cells is called magno cells. Magno cells respond to rapid movements. They are the cells that allow us to see life as a movie rather than as a bunch of still photographs. They transmit a quick series of images to the brain and help the brain see them as a continuous stream instead of seeing one image at a time. Researchers at NTNU believe that many learning disabilities are caused by problems with the way the magno cells work.
Professor Hermundur Sigmundsson and his group tested the theory that children who have significant problems with math often have a hard time seeing rapid changes in their surroundings. The study gave a math test to all of the 10-year-olds from two different schools. The highest and lowest scorers on the math test were also given a test to see how well their brains processed moving visual images.