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Developmental dyslexia (DD) is a neurodevelopmental disorder that affects 5-17% of children
.
A large number of studies have found dyslexia to have abnormalities in resting functional connections, but previous studies have mainly measured functional connections
in a time-averaging fashion.
Recently, more and more evidence shows that the functional brain network changes dynamically within a certain time frame, and the abnormality of the dynamic characteristics of the brain function network is closely related to cognitive dysfunction and is an important indicator of
brain disease.
Recently, in order to explore the relationship between the dynamic characteristics of functional connections and dyslexia, the research group of Hongyan Bi of the Key Laboratory of Behavioral Sciences, Chinese Academy of Sciences carried out a resting state functional magnetic resonance imaging study, using the sliding time window method to compare 22 children with Chinese dyslexia with 38 control groups of the same age (chronologicallyly) from multiple dimensions such as whole brain network, reading network, local node and unilateral connection age-matched controls (CA) Dynamic characteristics of resting state functional connections – temporal variability (Figure 1).
Dynamic functional connection analysis process A.
160 regions of interest and 28 reading-related regions of interest; B.
sliding time window method; C.
Whole brain network, reading network, local node, and unilateral time variability
It was found that at the whole-brain level, dyslexia children showed no difference
from children in the control group.
However, at the node level, dyslexic children had significantly higher temporal variability in functional connections in the left inferior frontal gyrus than in the control group, and this higher temporal variability was associated with poorer vocabulary, reading fluency, and phonological awareness (Figure 2).
Further analysis also found that this higher temporal variability of dyslexia mainly comes from the increased temporal variability of the functional connection between the
left inferior frontal gyrus and the bilateral occipital-temporal region (left midtemporal gyrus, left mid-occipital gyrus, and right cuneiform).
These results suggest that instability of brain functional connections in the left inferior frontal gyrus may be an important neural mechanism for
dyslexiagenesis.
Figure 2.
Dynamic functional connectivity at the node level
A.
greater temporal variability of dyslexia in the left inferior frontal gyrus; B.
temporal variability is associated with vocabulary, reading fluency, and phonological awareness
In addition, the study further investigated the relationship between dyslexia dynamic functional connectivity abnormalities and the functional and structural characteristics of local brain regions (Figure 3).
。 The results showed that the unstable dynamic functional connections of dyslexia in the left inferior frontal gyrus were related to their declining local activities, including amplitude of low frequency fluctuation (ALFF) and regional homogeneity (ReHo), and the dynamic functional connections partially mediated the relationship between local brain region activities and reading, revealing dynamic functional connections, The internal mechanism of the relationship between brain activity and reading.
Finally, the study found that the dynamic functional connections of the left inferior frontal gyrus were significantly associated with gray matter (GM) volume in the control group but not in dyslexia, suggesting that impaired dynamic functional connections of dyslexia may be related to
abnormal structural-functional coupling.
Figure 3.
The relationship between dyslexia dynamic functional connections and functional and structural characteristics of local brain regions
A.
The low-frequency fluctuation amplitude of dyslexia decline and its correlation with temporal variability; B.
The local consistency of dyslexia decline and its correlation with temporal variability; C.
The gray matter volume of dyslexia and its correlation with temporal variability; D.
The relationship between low-frequency fluctuation amplitude and vocabulary mediated by the time variability part; the relationship between local consistency and vocabulary mediated by the E temporal variability part
The study is the first to reveal abnormal dynamic functional connections in dyslexia children, which may result from impaired brain activity and functional-structural coupling
.
The study suggests a new neural marker for dyslexia, deepening researchers' understanding
of the pathogenesis of dyslexia.
The research was supported by the National Natural Science Foundation of China (31671155, 31800954), and related articles have been published online in Language, Cognition and Neuroscience
.
Yizhen Li+, Junjun Li+, Yang Yang* & Hong-Yan Bi* (2022): Disruption of dynamic functional connectivity in children with developmental dyslexia, Language, Cognition and Neuroscience.
https://doi.
org/10.
1080/23273798.
2022.
2129084
Source: Bi Hongyan Research Group, Key Laboratory of Behavioral Sciences, Chinese Academy of Sciences
