Professor’s Research Shines a New Light on the Neurology of Dyslexia
UC Merced developmental psychologist Jeffrey Gilger sees dyslexia less as a disease and more as an example of how the brain can develop differently from what is typical, and thereby represent what may be a “normal brain variant” in the population. Gilger recently published three articles taking a different look at dyslexia, which manifests itself as a phonological disorder – the brain doesn’t match sounds to the correct letter symbol – and affects people of all languages.
On average, estimates are that 7 percent of the school age population has dyslexia, with some studies suggesting even higher rates. Dyslexia runs in families and research has identified several genes that, along with environmental factors, may contribute to the risk for the condition.
Gilger, who has been on the UC Merced faculty for two years, has been using brain imaging to examine the neurobiological processes found in adults with dyslexia and a special group of dyslexics who are gifted in nonverbal (spatial) abilities.
In one study, he compared gifted dyslexics to a group of adults who were also gifted but normal readers. This study showed that while these two groups of adults performed similarly when taking behavioral tests, they use different neural processes or strategies to arrive at the same answers.
“This raises our awareness of how individual differences in neurology might be considered alongside behavioral observations when examining those with reading disabilities and/or giftedness,” Gilger said.
In another study, he was part of a team of researchers using brain imaging to see how adults with dyslexia perform when analyzing complex and dynamic spatial material unrelated to reading. The first study of its type, the results have shown that those with dyslexia seem to process this kind of information differently than those without dyslexia – just like they process reading material differently. This finding suggested that the brains of dyslexics are atypical in many areas – not only in those areas involved in reading.
Gilger is also the lead author on another first-of-its-kind study that compared brain activation patterns and behavioral tests in four groups of adults: those with a reading disability who are also gifted in nonverbal areas; those with dyslexia alone; those who were normal readers and also gifted in nonverbal areas; and a control group. Gilger found that gifted dyslexics resemble non-gifted dyslexics in reading, math and spatial behavioral tests, and in patterns of functional brain activation during word reading and spatial processing.
“This finding suggested that the reading disability and the nonverbal giftedness were not independent conditions,” he said. Rather, there could have been a lifespan interaction between the two skill domains, with reading compensation effects modifying how their adult brain processes text as well as spatial stimuli.”
Simply put, Gilger’s research shows that when undergoing these tests, the over-reliance of gifted dyslexics on atypical regions of the brain prevents the full expression of their nonverbal gifts.