Dyslexia, from the Latin which literally translates to “bad words”, is a disorder that impacts the ability to read well, comprehend written materials and even to spell and write properly. It’s the most common language based learning disability and it’s estimated that 70-80% of people who have poor reading skills are actually dyslexic. It occurs equally in males and females and across ethnic and socioeconomic lines, although children who have it and live in poverty or attend underperforming schools are less likely to get appropriate help. New research from a group of scientists from Boston University, Sargent College, MIT and Massachusetts General Hospital may have found the root of dyslexia in the brain and this new information might lead to better treatment.
There is a process in the brain called rapid neural adaptation and it goes on constantly in response to sensory cues in our environment. Whether it’s the sound of a song on the radio, a familiar voice, a taste of something new or a the feeling of our hand touching a rough surface, the brain processes all this input via rapid neural adaptation. Tyler Perrachione, assistant professor at Boston University’s College of Health & Rehabilitation Sciences, led the recent research into how dyslexia is related to this adaptation. Professor Perrachione, together with his colleagues at Sargent, MIT and Mass General, published their research December 21, 2016 in the journal Neuron.
The team first looked at study volunteers without dyslexia who were asked to pair spoken words with images on a screen while undergoing a functional MRI scan. When all the words were spoken by the same voice, brain activity showed an initial spike, but then stayed constant. When the second round was each word being spoken by a different voice, brain activity, which is evidence of rapid neural adaptation, spiked with each new and unfamiliar voice. The brain was working to adapt to the voice differences in pitch and tone. When the same task was given to study participants with dyslexia, their brains were almost in a constant state of activity. This increased activity showed that the brain of someone with dyslexia has to work harder to process the same input that the brain of a non-dyslexic person can easily parse. The differences in brain activity were especially noticeable in children between the ages of 6 and 9, who were just learning to read. In that group there was no adaptation at all to repeated words.
Expanding their experiments beyond spoken words, the team tried the same task but this time with pictures, written words and faces. Again, those with dyslexia had poor rapid neural adaptation to this stimuli as well. The results point to a paradox that has been puzzling researchers for decades. While those with dyslexia have trouble reading, there is no one specific part of the brain that processes just reading ability. Many areas of the brain are involved in the ability to read, so dyslexia must involve more than one part of the brain. The problem is likely across the spectrum stimuli to the brain, be it pictures, sounds, words or even odors and the sense of touch.
Perrachione’s team thinks that how people learn to read might be the problem. It’s truly one of the most complicated tasks the brain has to master. MIT neuroscientist John Gabrieli, co-author on the Neuron article was Perrachione’s PhD advisor. He explained, “There’s almost nothing we learn that’s as complicated as reading. That’s because learning to read is mentally cumbersome. The human brain did not evolve to read—literacy has been commonplace only in the last two centuries—so the brain must repurpose regions that evolved for very different ends. And the evolutionary newness of reading may leave the brain without a backup plan.” He likened dyslexia to pounding a nail with a stapler. It will eventually get the job done, but it’s a lot harder. Take a look at the video below to learn more about the study and what it might mean for the thousands that struggle with dyslexia.