Abstract
A universal signature of developmental dyslexia is literacy acquisition impairments. Besides, dyslexia may be related to deficits in selective spatial attention, in the sensitivity to global visual motion, speed processing, oculomotor coordination, and integration of auditory and visual information. Whether motion-sensitive brain areas of children with dyslexia can recognize different speeds of expanded optic flow and segregate the slow-speed from high-speed contrast of motion was a main question of the study. A combined event-related EEG experiment with optic flow visual stimulation and functional frequency-based graph approach (small-world propensity ϕ) were applied to research the responsiveness of areas, which are sensitive to motion, and also distinguish slow/fast -motion conditions on three groups of children: controls, untrained (pre-D) and trained dyslexics (post-D) with visual intervention programs. Lower ϕ at θ, α, γ1-frequencies (low-speed contrast) for controls than other groups represent that the networks rewire, expressed at β frequencies (both speed contrasts) in the post-D, whose network was most segregated. Functional connectivity nodes have not existed in pre-D at dorsal medial temporal area MT+/V5 (middle, superior temporal gyri), left-hemispheric middle occipital gyrus/visual V2, ventral occipitotemporal (fusiform gyrus/visual V4), ventral intraparietal (supramarginal, angular gyri), derived from θ-frequency network for both conditions. After visual training, compensatory mechanisms appeared to implicate/regain these brain areas in the left hemisphere through plasticity across extended brain networks. Specifically, for high-speed contrast, the nodes were observed in pre-D (θ-frequency) and post-D (β2-frequency) relative to controls in hyperactivity of the right dorsolateral prefrontal cortex, which might account for the attentional network and oculomotor control impairments in developmental dyslexia.
Highlights
Developmental dyslexia is defined when poor reading is accompanied by normal intelligence, adequate education, and a lack of other psychologically important factors [1]
Children who had difficulty reading, along with accuracy or speed in reading subtests of the DDE-2 battery and the “Reading Abilities” battery below the norm with a standard deviation of standardized data of normally reading children were included in the dyslexic group [85]
Like Medial superior temporal area (MST), inferior parietal lobe (IPL) responded to the speed discrimination
Summary
Developmental dyslexia is defined when poor reading is accompanied by normal intelligence, adequate education, and a lack of other psychologically important factors [1]. The shortcoming in the differentiation of speeds [6,7] is selectively related to the velocity factor on reading sub-skills, characterized by fluency and reading speed [8], but does not correlate with any measures for their accuracy, presuming that this deficit results neither from dysfunctions in visual nor from those in the attentional system in developmental dyslexia [9]. In this debut, the question still remains whether deficiencies in the processing of visual motion in dyslexia are specific to motion or are resulted from dysfunctions in the visual or attention systems [10]. In previous research of dyslexia, deficits in the processing of motion are related to a specific type of reading difficulty, underlying in each of them could be disturbed different neurocognitive mechanism [25]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
