White matter in the brains of children with dyslexia may be structured differently compared to typically developing readers, according to new research at Vanderbilt University.
For the study, published in the journals Brain Connectivity and Brain Research, researchers used neuroimaging to examine structural differences in connectivity in children with dyslexia as compared to typically developing readers.
The research involved 40 children ages eight to 17 years, 20 of whom had dyslexia and 20 of whom were typically developing readers. The researchers set out to visually map the structure of the brain in an effort to better understand the role of the thalamus in reading behavior.
Although many dyslexia studies focus on the cerebral cortex, the researchers of the new study targeted the thalamus region. The thalamus acts as the brain’s connector, relaying sensory and motor signals back to the cerebral cortex through nerve fibers that are part of the brain’s white matter. The thalamus also regulates alertness, consciousness, and sleep.
“A different pattern of thalamic connectivity was found in the dyslexic group in the sensorimotor and lateral prefrontal cortices,” said Dr. Laurie Cutting, professor of psychology and human development, radiology, and pediatrics at Vanderbilt.
“These results suggest that the thalamus may play a key role in reading behavior by mediating the functions of task-specific cortical regions. Such findings lay the foundation for future studies to investigate further neurobiological anomalies in the development of thalamo-cortical connectivity in individuals with dyslexia.”
In a related study, the team examined connectivity patterns in a cortical region known to be especially important for reading: the left occipito-temporal region, sometimes referred to as the visual word form area.
Cutting and her colleagues used diffusion MRI to study the structural connectivity patterns in the brains of 55 children.
“Findings suggest that the architecture of the left occipito-temporal region connectivity is fundamentally different between children who are typically developing readers and those with dyslexia,” Cutting said.
The typically developing readers showed greater connectivity in brain regions related to language than the dyslexic group. Those with dyslexia showed greater connectivity in regions related to visual word form and memory.
The researchers came from a variety of backgrounds, including faculty from pediatrics, engineering, radiology, psychology, special education, and other Vanderbilt departments and centers.
“This work also shows how collaborations between investigators with different expertise can lead to important discoveries and breakthroughs,” said Dr. John C. Gore, Hertha Ramsey Cress University Professor at Vanderbilt and director of the Vanderbilt Institute of Imaging Science.
“The interaction of developmental neuroscientists with imaging specialists was essential to produce these exciting results.”
Source: Vanderbilt University