Summary: Children with developmental language disorder have less myelin in parts of the brain associated with acquiring rules and habits, as well as brain areas associated with language production and comprehension.
Source: University of Oxford
Developmental language disorder (DLD) is an extremely common disorder, affecting approximately two children in every classroom.
Children with DLD struggle to comprehend and use their native language, facing trouble with grammar, vocabulary, and holding conversations.
Their language difficulties considerably increase the risk of having difficulties when learning to read, underachieving academically, being unemployed, and facing social and mental health challenges.
In research published in the journal eLife, Dr. Saloni Krishnan and colleagues used MRI brain scans that were specifically sensitive to different properties of the brain tissue.
For example, the scans measured the amount of myelin and iron in the brain. Myelin is a fatty substance that wraps around neurons and speeds up transmission of signals between brain areas. It is like the insulation around electrical cables.
The research demonstrated that children with DLD have less myelin in parts of the brain responsible for acquiring rules and habits, as well as those responsible for language production and comprehension.
Dr. Krishnan (Reader, Royal Holloway, University of London), who led the study as a Research Fellow at the University of Oxford, says that “DLD is a relatively unknown and understudied condition, unlike better known neurodevelopmental conditions such as ADHD, dyslexia, or autism. This work is an important first step in understanding the brain mechanisms of this disorder.”
Senior author Kate Watkins, professor of cognitive neuroscience at the University of Oxford, says that “this type of scan tells us more about the makeup or composition of the brain tissue in different areas.
“The findings might help us understand the pathways involved at a biological level and ultimately allow us to explain why children with DLD have problems with language learning.”
More studies are needed to determine if these brain differences cause language problems and how or if experiencing language difficulties could cause these changes in the brain.
Further research may help scientists find new treatments that target these brain differences.
Quantitative MRI reveals differences in striatal myelin in children with DLD
Developmental language disorder (DLD) is a common neurodevelopmental disorder characterised by receptive or expressive language difficulties or both. While theoretical frameworks and empirical studies support the idea that there may be neural correlates of DLD in frontostriatal loops, findings are inconsistent across studies.
Here, we use a novel semiquantitative imaging protocol – multi-parameter mapping (MPM) – to investigate microstructural neural differences in children with DLD.
The MPM protocol allows us to reproducibly map specific indices of tissue microstructure. In 56 typically developing children and 33 children with DLD, we derived maps of (1) longitudinal relaxation rate R1 (1/T1), (2) transverse relaxation rate R2* (1/T2*), and (3) Magnetization Transfer saturation (MTsat). R1 and MTsat predominantly index myelin, while R2* is sensitive to iron content.
Children with DLD showed reductions in MTsat values in the caudate nucleus bilaterally, as well as in the left ventral sensorimotor cortex and Heschl’s gyrus. They also had globally lower R1 values. No group differences were noted in R2* maps. Differences in MTsat and R1 were coincident in the caudate nucleus bilaterally.
These findings support our hypothesis of corticostriatal abnormalities in DLD and indicate abnormal levels of myelin in the dorsal striatum in children with DLD.